Proposing a Handbook: High Level Adventure Design

[ksbsnowowl]

I'm running a 19th level gestalt game, and I've found that there is very little actual advice concerning running a game at such a level.  There is some vague advice, such as "don't run it like a dungeon crawl with bigger numbers," but actual advice and suggestions that might spark some ideas... those are pretty few and far between.

There also aren't very many examples of published adventures at that level to use as a template for what challenges are appropriate.  The latter parts of City of the Spider Queen, and Bastion of Broken Souls are about it, as far as third edition are concerned.  There are also some third party adventures, I'm sure (World's Largest Dungeon, for example, but that doesn't show you how to build a story laced with encounters, which is what many campaigns, or at least mine, try to emulate.)

This blog post has some decent thoughts on epic level encounter design, though it is written from a 4e perspective.  The blogger's stance on "bigger is better" gets a little past the point of extreme, but it is worth a read:

The Big Ideas

Alright, so you have in mind some basic guidelines that will help you towards good ideas, now where do we get them? Start with books, movies, videos games and the like and then practice a bit of one-upmanship. How far you’re willing to go will depend upon the tone of your game, but at this level I’m saying go big or go home.

Here is a notable example of famous action sequence and how the stakes could have been raised – Independence Day. Remember the scene where the alien mothership was beaming huge lasers to destroy the planet? Instead of simply killing people, the high beams could have coupled as mind control lasers, turning all life into thralls for the space invaders. This means that the important NPC that the characters could be trying to protect could be turned, so that they would have to negotiate their compromised NPC, fight off an army of innocent mind slaves and an army of aliens, as well as deal with the mothership. How does that sound? Pretty boring right?

Ok, so to up the ante, the NPC is the vessel of a god that the aliens are trying to prevent from reaching the sacred temple so that the god cannot ascend. In order to do this the aliens (who might was well be Orcs or Mind Flayers now) teleported the whole temple onto a collision course with a near by star. As a result the PCs have to manage this battle while it draws ever closer to a glowing orb of fiery death. To make matters worse there’s no breathable air in D&D space so the PCs have to leverage their magic items, special abilities and clever thinking to even hope to survive long enough to risk being burnt to death in the sun. How dull.

While their temple asteroid races through space towards becoming a spatial singularity, it passes through meteorite swarms, electrical storms and gets blasted by arcane radiation from the star. On given rounds random square are hit with these space missiles, struck with lightning, or burnt by solar flares. PCs with the right abilities, racial background or items can harness this power to deadly effect against their enemies or be killed horribly. Yawn, I think I’ll sit this fight out.

The evil henchmen boss jumps down from the Mind Flayer sky city (complete with mind controlling anti-momentum beams) and joins in the fray, successfully stealing the soul from the important NPC, and thus becoming a super boss, the powerful deified forces cause the creature to grow to enormous perorations, becoming an 10×10 creature, tentacles a flare, commanding the hordes of low level thralls to swarm the party. Their numbers are so great that the hordes are best treated as a terrain type, being too numerous to actually be slain. The PCs are flanked everywhere they go, grasping limbs acting as difficult terrain, but offering up hearty bonuses to any attack. I might roll up a character, come to think of it.

The PC’s finally manage to best the massive Mind Flayer, it’s body being cast into the dark void of space. Seemingly victorious, the PCs catch their breath as the thralls recover from their trance. Off in the distance there’s a noise of a crackle and a crunch (there can be sound in D&D space). To the horror of the party, the body of the slain Mind Flayer has collided with a near by moon, the darkness of it’s soul is transforming the galactic body into a plane of pure hate. The moon begins to rotate more quickly, moving towards the party and their temple asteroid at a frightening pace. This could either be a skill challenge if you need a break from the initiative order, or it could be time for the party to finally kill a planet.

...

I could go on, but I’m sure the premise is already too ridiculous for most. The key will be to find the point at which you say to yourself “That’s too much, even for me!” and then stop there.

Like I said, past the point of extreme, but still not a bad illustration.  Believe it or not, that blog post is the best advice I've found thus far in the last few days of searching.

The god-stealing mind flayer invasion isn't going to work for some campaign types (my Viking-themed game included), but some of the aspects that he mentions can certainly be adapted:
Making the threat multi-faceted (mentally-enslaved army plus alien army, etc).
Some sort of mob or swarm acting as difficult terrain, or positioning innocents such that they restrict what actions the PC's can take if they want to avoid killing innocents.
Adding thematically-appropriate terrain features, such as a meteorite shower, or fighting in a storming thundercloud, would add to the difficulty, if only because it forces the PC's to use resources and actions to deal with the additional complication.

I'll freely admit, I've been a bit guilty of the "dungeon crawl with bigger numbers" problem as my PC's hit the mid-teens; many of their adventures of late have been MacGuffin quests where they just sneak in and ambush the bad guys.  There is a paradigm shift that is difficult for many DM's to recognize or handle correctly.

That's why I want to make this resource, so this tricky aspect of DM'ing can be nailed down a bit more concretely.  Heck, even WotC hasn't given much good advice in this regard; one of their blog posts from November 2012 talked about how they thought long and hard about capping D&D Next at 10th level.  So any help or insight you all could suggest as far as high level adventure design goes, I and hopefully others would be grateful.  I don't want this to be too vague; rather I want some solid examples of the elements that should be employed to keep the game challenging, while maintaining a story that makes sense.

[ksbsnowowl]

This blog post relates to encounter design in general, not necessarily at high levels, but it might be something else to include.  I think he makes some fair points, some of which I plan to make use of this next week (how about some 14th level warring mooks?)

[phaedrusxy]

Good idea, and something that is sorely needed, as doing this in D&D is actually incredibly hard, unless you as the DM have vastly more experience and rules knowledge than the PCs (and even then, it can be tricky as they'll undoubtedly blunder upon powerful combinations). No time to help right now, but I'll try to remember to come back.

[ksbsnowowl]

I did just think of one other book that has examples of high-level challenges: Elder Evils.

Now, an elder evil isn't going to be right for every campaign, but the encounter set-ups might provide some insight.  I'll have to give that a perusal again when I get a chance.

Oh, thought of one other thing that would be a good idea to cover:
RAW vs RAI of Mind Blank.  RAW, Mind Blank + Improved Invisibility makes it VERY hard for the bad guys to deal with the PC's (c'mon, not every bad guy mook can have Mindsight...)  RAW, it stops foes from finding you with See Invisibility or True Seeing, which I don't think was ever the intention.  Invisibility Purge is the only Core spell that can deal with it.  Change Improved Invisibility to Superior Invisibility and the only thing that can deal with it at all is Zone of Revelation, simply because it isn't listed in the laundry list of exemptions in Superior Invisibility.

I went with the RAW interpretation on Mind Blank for my gestalt game, and that has been the biggest impediment to being able to challenge my players.  In the future I'm going to use the RAI - it blocks divinations that target the Mind Blanked individual (ie - scrying, discern location), but not spells that are affecting someone else by enhancing their senses.

[nijineko]

I've been running a campaign for a few years now, during that time they've gone from 16th level to 19th and 20th depending on the party member. furthermore, i usually run high level campaigns into the epic. i think i might have some useful feedback, but i'm at lunch, so i'll also have to try to remember to come back and comment.

so, what is the currently interpretation of RAW for mind blank considered to be? i might have some sneaky ideas around that.

[ksbsnowowl]

so, what is the currently interpretation of RAW for mind blank considered to be? i might have some sneaky ideas around that.

This spell protects against ... information gathering by divination spells or effects.

The problem is that "information gathering" is so vague... True Seeing allows you to gather information about things within range, specifically visual information.

Now, Nondetection is much more explicit:

If a divination is attempted against the warded creature or item, the caster of the divination must succeed on a caster level check (1d20 + caster level) against a DC of 11 + the caster level of the spellcaster who cast nondetection.

"If a divination..." would include ALL divinations, but at least it can be beat with a CL check.

I read through many, many threads on the subject before deciding how I was going to run it in my game, and the general consensus (about 65 - 70%) is that True Seeing is blocked by Mind Blank.

Oh, and don't worry if you don't have time to help right away.  I see this as a long-term project.  I'm not planning to whip this out in the next few weeks or anything.

[nijineko]

The subject is protected from all devices and spells that detect, influence, or read emotions or thoughts. This spell protects against all mind-affecting spells and effects as well as information gathering by divination spells or effects.

True Seeing
Divination

True seeing is a divination effect, ergo it is blocked plain and simple, and not because of any vague debatable 'info gathering' qualities. though i guess the debate is whether "seeing something the way it really is, rather than how it presents itself" qualifies as information gathering... i'd imagine the people who argue against it are trying to use the skill description to show that it doesn't qualify as info gathering? i'm pretty sure that learning what is really going on counts as in increase in total information.

Touchsight on the other hand is psychometabolism which is the equivalent of transmutation and thus is unable to be blocked by mind blank. and a whole lot more easy to come by than, say, mind sight.

[oslecamo]

I have my handbook for DMs, that altough more general, includes advice for high level monsters and terrain.

Some advice from my experience tough:
-High level parties have high mobility. A mile isn't a trouble. Going to the other side of the planet or another plane is expected.
-Multiple simultaneous threats help keep the party challenged, since single threats can be easily solveable by the player's ever increasing toolbox.
-Death's revolving door. People die and get back.

The subject is protected from all devices and spells that detect, influence, or read emotions or thoughts. This spell protects against all mind-affecting spells and effects as well as information gathering by divination spells or effects.

...
Touchsight on the other hand is psychometabolism which is the equivalent of transmutation and thus is unable to be blocked by mind blank. and a whole lot more easy to come by than, say, mind sight.

As bolded, mindblank isn't limited to divination effects. Any effect that gathers information will be blocked. Including touchsight.

Of course, if you go with reading that true sight is blocked by Mindblank, then mindblank=autowin. Because with that reading,  even spot and listen basic skills fail to work. You cast mindblank, nobody can gather any information about you, and if you include that just looking at you counts as information, then you don't even need superior invisibility, you just can't be detected at all.

[ksbsnowowl]

I'm pretty sure the "... or effects" is meant to be an addendum to "spells," as you can have a divination effect that isn't a spell (an SLA or a Supernatural Ability*).  Spot and Listen are not divination, which has a defined quality within the game.  That definition even specifies that it is "spells," which explains the addendum of "... or effects" to the statement.

*For example, an Erinyes' True Seeing Supernatural Ability.

[MetroMagic]

I don't want this to be too vague; rather I want some solid examples of the elements that should be employed to keep the game challenging, while maintaining a story that makes sense.

Great idea! I’ve been running high level games; I like my players simply to play their favorite character, whatever that means. I don’t want to constrain their imaginations; it’s exactly my task to deal as DM.

Here are some specific favorites for me and the players:

---Tough puzzles, open ended with no clear answers. Not riddles, instead complex situations the players have to solve. I had a player show up once with the God Of Magic. He could do anything. But when the party had to solve their situation, and the player said “I’m the God Of Magic, I can do anything!” I as the DM still said, “OK, fine, but what do you do?” The players still had to solve the situation. As a corollary: Imagine situations where the assumptions and practiced approaches of experienced players may work against them, while novices might succeed; this will require careful play by the PCs not to be led astray.

---Opponents with vast resources and extreme subtlety. By 19th Level, you’re not merely fighting Illithids; if you’ve survived to that point, by then you’re wanted by the Illithid Empire. It’s not hard to build sensible plot lines that scale up as the campaign progresses, especially if you plant seeds in advance to presage the later developments – or reinterpret mysterious clues you left behind with new, deeper significance. High powered PCs have high powered information gathering, so there is plenty of game logic to reveal layer after layer of the onion while still keeping mysteries hidden. Also remember that the opposition has higher and higher powered defenses. The creatures powerful enough to be running an Empire have had millennia to develop their subtlety. Remember that big baddie you killed at L15, and wiped out his army while you were at it? He was just a minion, sent to test your capabilities and reveal your strengths and weaknesses… That’s what you learn at L18, when your opponents hit you with coordinated, carefully tailored attacks...

---NPCs who are very helpful and very powerful, even may be more powerful than the PCs (because how did those NPCs survive to get to that power level; they must be very careful and really good at what they do) – it’s the other side of the “opponents with vast resources” principle – but who can’t solve the party’s problems. Always keep the focus on the PCs. Nuff said.

---A politically complex mess of third party NPC players who are pulling on the threads to shape situations to their own interests. Demigods, angels, Princes of Hell, whatever fits, and even things that don’t seem to fit. Keep your players guessing. Drop little hints that justify later big surprises as other plotlines emerge. By the time the PCs get to the upper teens in level, and certainly by Epic levels as they move toward godhood-level powers themselves, some of the creatures they meet – or have to deal with in some way – will not be mere mortal creatures either.

---Back to the first point: I don’t want to constrain the players’ imaginations; it’s exactly my task to deal as DM. I want the game still to be OK in case the PCs’ power level scales up toward an asymptote. My favorite response to “You mean I can do this? REALLY?!? (Come on, guys, how can the DM let me do this? I never thought he’d say yes.)” is “You’re going to need it.” As DM you also have to let the PCs *use* their awesome power, because otherwise what’s the point of having it? So there needs to be a range of opponents.

I’ll give you a specific example from a game where I played a PC, A main baddie was trying to commit deicide and take over, starting by trapping the deity’s devas, with the Deva of Divination first, of course. There were four devas trapped in a frozen pond of water in the River Lethe which kept them effectively unconscious, on a deep layer of Tarterus; the freeze was being held in place by a band of demons with that ability. The guards were a small army of Yugoloths of varying abilities, all very nasty, especially since magic didn’t bother most of them very much. How were we to pull off this rescue? The DM had no idea. It was an amazing assault. Six high level characters, careful planning, pooled resources, a little help from outside, and a lot of luck. One of the best games I’ve had the privilege to play.

The god-stealing mind flayer invasion isn't going to work for some campaign types (my Viking-themed game included), but some of the aspects that he mentions can certainly be adapted

Vikings… lots of mythology tropes to draw on, for a rich plot line. The Nordic pantheon and the tensions within it. The Norns messing with… almost anything makes sense. If you don’t have these elements in your current setting, suppose an alternate Viking-themed Prime was trying to move in on yours? Or crossovers have begun innocently in ways no one yet fully understands? Maybe all the Planes-hopping your PCs have been doing is starting to attract attention, or causing some type of a breakdown…

Heck, even WotC hasn't given much good advice in this regard; one of their blog posts from November 2012 talked about how they thought long and hard about capping D&D Next at 10th level.

I’m not surprised. They’re more rule-bound than anyone. They have the greatest vested interest in purity of the system. As DMs we’re free to imagine whatever we like. And I think you can tell from their backstory writing that their idea of a big sweep of scope is often a mere few hundred years, in their modules and other backstory products. By contrast, the challenges for the PCs could be very different, where at L19, no matter how much power they can throw around, they could still be out of their league, severely challenged, and just scratching the surface of knowledge. But WOTC pretty much doesn’t go there, or just doesn’t want to take DMs there.


OK, that’s more than enough for now.

[nijineko]

The subject is protected from all devices and spells that detect, influence, or read emotions or thoughts. This spell protects against all mind-affecting spells and effects as well as information gathering by divination spells or effects.

...
Touchsight on the other hand is psychometabolism which is the equivalent of transmutation and thus is unable to be blocked by mind blank. and a whole lot more easy to come by than, say, mind sight.

As bolded, mindblank isn't limited to divination effects. Any effect that gathers information will be blocked. Including touchsight.

doesn't that kinda ignore the rules of english grammar to get that reading out of that sentence? the "by" indicates what will qualify as info gathering, i.e.: divination spells or effects. the or indicates that divination is being broken into two categories, i.e.: spells, effects and that neither are effective. effects is a subset of divination, and thus could not be stretched to mean anything other than divination by the grammar of that sentence.

(however, as wotc is infamous for poor grammar and word choice, i guess that won't mean a whole lot to some people.) ^^




oh, and while i'm posting, i'll toss in a few points at the OP.

i've found that variety is the spice of life at high level. i will toss a straightforward if challenging combat at them at one moment, a sneaky type the next, a can't-be-killed-by-hp-damage the next, an RP challenge where combat is a useless answer but skills, info gathering, and cunning will pay off after that, a series of puzzles another time, a mass attack by kooks, a riddle, a chain-quest, a very powerful BBEG with minions, another adventuring party, things where convention is defied and turned on its head, alien settings, exotic locales, strange and unusual NPCs, bizarre backdrops for exploration and/or combat with oddball rules (gravity, time, space, tesseracts, etc.,)a tea party, stumbling into a fairy tale with twists, rescuing a cat from a tree, chatty Powers out for a stroll, prophecies, consequences of past choices coming back to roost, a dungeon crawl courtesy of grimtooth, and so on.

my players never know what they will run into next.

also, i play by the rule of yes, for the most part. there are a few things i don't like, but by and large almost all of 3.x is open to them to use. it is amusing to show them their character's weaknesses and shortcomings, and it is great fun to see them thrash my encounters, or to puzzle out a new solution they hadn't thought of before.

[ksbsnowowl]

A good post with lots of info; sorry it took me so long to respond.
A few thoughts:

---Tough puzzles, open ended with no clear answers. Not riddles, instead complex situations the players have to solve. I had a player show up once with the God Of Magic. He could do anything. But when the party had to solve their situation, and the player said “I’m the God Of Magic, I can do anything!” I as the DM still said, “OK, fine, but what do you do?” The players still had to solve the situation. As a corollary: Imagine situations where the assumptions and practiced approaches of experienced players may work against them, while novices might succeed; this will require careful play by the PCs not to be led astray.

I did this back around 14th level.  The stakes of the puzzle were very high, and they chose... poorly.  They all died.  I've described the situation elsewhere on these boards, and some thought I made the puzzle too hard, or the repercussions too high; others thought it was an appropriate challenge.  Regardless, my players did not enjoy it.  But they also approached it with a lot of hypothesis and misconceived understandings, and not much careful exploration and testing.

Maybe next time there is a puzzle, they will be more cautious as they figure it out.

That's not to say tough puzzles don't have their place.  But some players will detest them.

Vikings… lots of mythology tropes to draw on, for a rich plot line. The Nordic pantheon and the tensions within it. The Norns messing with… almost anything makes sense.

I've used quite a bit of inspiration from the Sagas.  They've dealt a lot with the Vanir (there isn't a whole lot on info on them from the Sagas, so I have modeled them after the Seelie and Unseelie courts), they are dealing with a lingering problem of Andvari's cursed treasure, and they are soon to get their hands on Sigurd's sword, Gram.

My setting is placed in a time where Loki is already bound.  In epic levels they'll have to deal with a Fire Giant plot to kickstart Ragnarok by covering Midgard in Fimblewinter.

[phaedrusxy]

I have put PCs into situations where I actually didn't know how (or really if, for certain) that they would get out.  I've only done this with high powered/leveled/optimized PC groups, but so far they haven't let me down. 

For example: they came out of a portal inside of a collapsed building within a dead magic zone (which filled the entire accessible area), in which there was a hellwasp swarm and a lot of dead bodies (from other fools who'd came through that portal...), including one dragon, which the swarm was currently inhabiting. I did leave cracks to the outside that they could peek out of, so that they knew that freedom/survival was close enough to see/smell/taste... but just out of reach. I thought they'd probably have to resort to just beating their way through the rubble (which IIRC they did), but wasn't actually sure if they'd immediately go to this as an option (or at least not quickly enough to avoid death ).

[Endarire]

Perhaps this will help: Challenging 3.5 and Pathfinder Parties in Practice (Word 97 Doc)

In the campaign I GMed the majority of, we ran levels 1-21 and would've been 22 after the end fight.  The final fight was against the God of Death (Nerull) in a perpetual time stop where the NPC helper Wizards were performing a cerermony and had surrounded themselves in an antimagic field inside a wall of force cage.  The party won by plot, with a helpful demigod possessing one of the party's Sorcerers and countering every spell Nerull cast.

In that campaign, leading up to the final fight, the party did go planes hopping.  It was necessary to awaken the Primal Elementals (of which the group entered the Water for a spiffy boss fight which was made drastically easier due to me misunderstanding how Elementals should be immune to poison, and that the group communicated to the Primal Earth Elemental - which was part computer - via an IRC setup and 2 real life computers) and reunite both halves of the world of Xeen into a single spherical planet.  Additionally, the group was given scrolls of dimensional lock with which to seal the inside of a spaceship, then frantically had to dispel a section to be able to teleport out before the ship self-destruct.  (Oh, the loveliness of players having to get out of a mess they made for logical reasons!  I was quietly cheering them on internally.)  Mind you, the Xeen campaign had lots of humor and gamisms; the final area required completion of a 3D crossword puzzle (10x10x10) to advance (which the group just skipped due to disinterest), a series of reverse binary translations, sudoku, star mapping puzzles, and a lot of puzzles, minigames and events that existed to break the expectation of combat-rest-social that was prevalent in D&D 3.5.

There were gimmick battles too, such as meeting with another adventuring party atop a tower (for a total of 12 PCs) where enemies were teleporting in rapidly.  The group could've stayed and fought a dracolich at that point (they were each about level 7) but they didn't.  Fast forward a few levels, and the group (about 7 PCs) fought an aerial battle against this dracolich (which was optimized by me) riding Sky Golems, beings of my own invention.  Think permanently flying Iron Golems with higher stats and permanent freedom of movement for an idea.  They prevailed, though at the cost of 2 very expensive Sky Golems (a market value of 2+ million GP each).  After that, the owner of these golems (Ellinger, because) refused to let them near his beloved inventions.

When it came to combat in Xeen at high levels, I made templates of enemies with pre-buffed stats.  I used a lot of Necropolitan Wizards and Wizard/Incantatrixes.

Intraparty balance-wise, the group got introduced to the Deck of Many Things about level 10.  The group's Paladin pulled an XP card and gained about 2 levels in 1 go.  It also helped that everyone else was a cast-heavy gish or a full caster, or, in one case, a Swordsage-based martial adept.  (The group hit level 15ish around the time Tome of Battle came out.  I redid the NPC adventuring party as a group of level 15 martial adepts where appropriate.)

Some challenges I've discovered since then:
-Wild magic zones.
-Energy transformation fields.
-Give the PCs (and by extension, the players) power but make them uncomfortable using it.
-Involve the planes.  D&D's multiverse is too big not to be explored, and D&D's power level is too big not to move the higher-power beings off-world.
-Play your plot card.  Some things are just reserved for the plot and outside the realm of PC control.  Developing a planar seal (for another campaign) made by powerful extraplanar beings (angels, Wizards, maybe gods) that prevents all extraplanar travel (except perhaps summoning) will change things.  Leaving very specific portals to bypass this seal works.  Also, making these portals 1 way may cause PCs to think twice before going through.  (Though the plot may call 'em through.)

Additionally, consider these high level adventures (level 16+) for 3.x/Pathfinder (gotten here):

(click to show/hide)

Level 16
 

• Demonblade (Dungeon #97)
• Rock and the Hard Place (Dungeon #91)
• Bright Mountain King (Dungeon #142)
• The Library of Last Resort (Dungeon #132)
• Thirteen Cages (Dungeon #114)
• Black Rain (WotC website)

Level 17
 

• Into the Maw (Dungeon #147)
• The Twisted Run (Dungeon #129)
• The Greater Halls (Dungeon #139)
• The Haunting Lodge (WotC website)
• The Thunder Below (WotC website)

Level 18
 

• Diplomacy (Dungeon #144)
• Gates of Oblivion (Dungeon #136)
• Kings of the Rift (Dungeon #133)
• The Lich-Queen's Beloved (Dungeon #100)
• Root of Evil (Dungeon #122)
• Strike on Shatterhorn (Dungeon #115)
• Vlindarian's Vault (Dungeon #141)
• Wells of Darkness (Dungeon #148)
• Force of Nature (WotC website)
• War of Dragons (WotC website)
• Prisoner of the Castle Perilous (WotC online Dungeon #153)

Level 19
 

• Asylum (Dungeon #116)
• Enemies of My Enemy (Dungeon #149)
• Into the Wormcrawl Fissue (Dungeon #134)

Level 20
 

• Dawn of a New Age (Dungeon #135)
• Prince of Demons (Dungeon #150)
• The Razing of Redshore (Dungeon #92)
• Heart of Hellfire Mountain (Dungeon #140)
• An Icy Heart (WotC website)
• The Essence of Evil (WotC online Dungeon #152)[/l][/l][/l]

Alternatively, what about Age of Worms or Shackled City?  What about Googling "D&D 3.5 Level 17 Adventure"?

[PlzBreakMyCampaign]

I find they are much easier without 9th level spells. There's the same gap between 8 and 9 that there is between 3 and 4, imo

[Endarire]

Please explain the great rift in power between level 4 and 3 spells.  Level 8 & 9 I understand.

[ksbsnowowl]

Please explain the great rift in power between level 4 and 3 spells.  Level 8 & 9 I understand.

I assume he is alluding to the reason why E6 caps at 6th level.  Fourth level spells allow you to bring the dead back to life, allow you to bypass mundane fortifications, allow you to communicate and pass information over long distances, allow you to gain massive stat bonuses via shape-changing magic, allows you to call outsiders, etc.

In essence, the type of game you can play changes once you get 4th level spells.

Oh, thought of one other thing that would be a good idea to cover:
RAW vs RAI of Mind Blank.  RAW, Mind Blank + Improved Invisibility makes it VERY hard for the bad guys to deal with the PC's (c'mon, not every bad guy mook can have Mindsight...)  RAW, it stops foes from finding you with See Invisibility or True Seeing, which I don't think was ever the intention.  Invisibility Purge is the only Core spell that can deal with it.  Change Improved Invisibility to Superior Invisibility and the only thing that can deal with it at all is Zone of Revelation, simply because it isn't listed in the laundry list of exemptions in Superior Invisibility.

Some more on this subject.  I recently came to the realization that Mind Blank + Superior Invisibility isn't as automatically game winning as most people seem to have treated it as.  The reason?  Mind Blank does not affect objects, only a creature.

There are several spells which specify they affect a creature's gear in addition to the target creature (Resist Energy, Invisibility, Nondetection).  Mind Blank has no such clause, and as such is does not protect a creature's gear.  If a Mind Blanked and Superior Invisible PC is viewed by a fiend with True Seeing, the fiend will still see all the PC's gear (much like the Levi's Jeans commercials from the late 90's), though he will not see the PC.  At worst, a PC that wears an average amount of clothing would gain an ad hoc 10% miss chance.

Nondetection works better against True Seeing in this regard, as it will affect the target creature's gear, but there is a caster level check involved, so a True Seeing creature has a chance to still see the PC and his gear.

Similarly, any active spells on a Mind Blanked on Nondetectioned PC will still produce magic auras that can be seen via Arcane Sight.  The PC would gain a 50% miss chance from total concealment, but the bad guy could see what square to attack.

This interpretation still allows the combo to be effective a lot of the time, but doesn't completely prevent a DM from challenging the PC's.