The Armor Class Handbook (WIP)

[sirpercival]

WIP.  A lot of people come asking for help on boosting their AC, and we don't have a handbook, so I'm going to make one.  I've picked up a few tricks on how to increase AC for a few different character types, so I figure why not compile them?

Discussion Thread

Things to do:
~Compile list of all sources of given bonus types.
~Calculate average attack bonus as a function of CR

Normal color coding: navy is an excellent choice, blue is a good choice, black is a good choice, and red is a poor choice.

Basic Strategies

Wear heavier armor.  This is the most basic and intuitive way to increase your armor.  However, it's only a good choice if you've completely dumped Dex -- in general, increasing your Dexterity will give you much better overall results.  There are also diminishing returns -- you can only get a bonus so high by going heavier, while boosting Dex is theoretically unlimited.

Boost your Dex. This is one of the easiest and best ways to boost your AC.  Con: doesn't apply to your flat-footed AC.  Pros: applies to your touch AC, which is more important and harder to boost; adds to initiative, making it more likely you'll go first and not be flat-footed (and win rocket tag); adds to Reflex saves, which helps with AoEs that bypass AC anyway.

Grab multiple bonuses. Bonuses of the same type do not stack, but you can still work up a respectable AC even at low levels (when CLs for AC-boosting spells are low) by having several different bonus types.

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AC for the Mundane Character

Mundane characters don't have many options in terms of boosting their AC, so it's mostly going to come down to equipment.  The most basic strategy is befriend a spellcaster.  As in so many other situations, spells rule all.

Low-level (1-6) strategy

Eternal Wands.  These will be your friend, since you can use them without spending ranks on UMD.  Grab eternal wands of barkskin, alter self, cat's grace, magic vestment, and (later on) polymorph.



Mid-level (7-14) strategy

At this point you can look into getting different ability bonuses to AC from prestige classes.  Equipment and buffs are better, since they go with everything, but this sort of thing is definitely possible.

Make sure to get a shield like the one described for arcane caster below, but instead of a Twilight shield, you can get an Animated shield and still use 2-h or TWF fighting styles.

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AC for the Arcane Spellcaster

As an arcane spellcaster, you have lots of options (as in every other situation), though not quite as many as divine casters.  Strongly consider getting Magic Vestment on your class list -- the Halfling domain has it (as well as Freedom of Movement at 4th level), as well as a few other domains.


Low-level (1-6) strategy

Mage Armor, the most basic way to protect yourself at low level.  This is a long-lasting, 1st-level spell that will be a staple of your repertoire for some time.  It's better than a chain shirt, with no ASF or ACP, and it applies to incorporeal touch attacks.

Shield, another staple.  Sadly, its duration is only 1 min/level, so it isn't as good as mage armor, but it does block magic missiles, and it never goes out of style since there's no higher-level version of it.  At higher levels you can persist this spell for a free +4 shield bonus to AC (including vs incorporeal touch attacks) and immunity to magic missiles.

Alter Self is amazing in so many ways... this spell can increase your natural armor bonus drastically.

Scintillating Scales (Sor/Wiz 2, SpC), when combined with Alter Self, converts your natural armor bonus to a deflection bonus, which applies to touch attacks.



Mid-level (7-14) strategy

Once Polymorph comes online, the game changes (even more so with Draconic Polymorph).  You can get high Dex and high natural armor with the same spell -- sometimes you can get deflection instead (will o' the wisp), or you can rock Scintillating Scales.  One of the most broken spells in the game comes through again.  If you can manage CL 15, get a Sand Giant for a 21 Dex and +11 nat armor.

A Lesser Rod of Chaining should become available in this range, as well.  Get it, you want it.

Darkwood Shield.  That's right, I said a shield.  You can start thinking about something like a darkwood spiked heavy shield, with the shield enchanted +1 twilight ghost ward (no ACP, no ASF) and the spikes enchanted +1 defending (and when you get the money, eager and warning as well; you can even drop a wand chamber with a wand of Nerveskitter in there for a nice fat +12 to init).  Then a magic vestment on the shield and a GMW on the spikes (you're now high enough level to start enjoying that) can give you a +4 or +6 to both AC and touch AC, more with CL boosters.

Robe of Arcane Might.  Get +1 CL for your specialty school, as well as a +4 armor bonus to AC.  It's a robe so you can hit it with Magic Vestment, and arguably can get it enchanted (run that one carefully by your DM, referencing the Bracers of Armor deal in the A&EG).  If you don't like that, then a +1 ghost ward twilight mithral shirt is your friend, with a chained MV on your shield.  Hell, throw in armor spikes and get those enchanted +1 defending as well -- if your DM is okay with multiple defending weapons stacking.



High-level (15-20) strategy

Make sure you have your armor and shield at this level, because now MV & GMW really get going.  A 20-CL MV and GMW on your shield alone nets you +10 to AC and touch AC.

Draconic Polymorph and Shapechange rock my world.

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AC for the Divine Spellcaster

Divine spellcasters get the best set of spells for defense, of course.  Lots of different bonus types available, and if you can get access to the Transformation domain, you even get Alter Self, Polymorph, and Shapechange.  Archivists get the best spell list, so will have the most different options; Druids get wild shape, which is essentially free polymorph (though the best natural armor bonuses are with other creature types).


Low-level (1-6) strategy

Armor and shield. You're proficient with armor, so wear it.  However, I have to reiterate that Dex is better than heavy armor.  So wear lighter armor (especially if you're a CC or Archivist) and have a higher Dex.  Use a shield, too.  Why not?

Barkskin and Shield of Faith work very nicely at stacking multiple bonus types.  If you do get Alter Self, Barkskin should stack.

Guardian Spirit is a relatively low-level source of insight bonus to AC, if you have the Incarnum Spellshaping feat.



Mid-level (7-14) strategy

You can do some of the same tricks that arcane spellcasters do, though you don't need Twilight on your armor or shield.

Armor of Darkness is a good upgrade over Shield of Faith if you can get it.

Druids and archivists can improve on Barkskin with Tortoise Shell, though it slows you down.



High-level (15-20) strategy

With CL boosters, Mantle of the Icy Soul + Algid Enhancement is now an improvement on Armor of Darkness, and grants extra benefits.

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reserve #4

[sirpercival]

reserve #5
 (that's probably enough.)

[Tshern]

I worked on something similar back in the day. It could have a few items you haven't put in yet, so feel free to use that for referencing.

Edit: Urgh, just saw the discussion thread...

[sirpercival]

Lol no problem.  I will definitely take a look at it, and probably scavenge a bunch... this is nowhere near finished.