First game - some questions

[Krika]

So, I am hopefully going to be DMing for the first real time in a PbP game with a bunch of friends soon, and I wanted to consult the general wisdom of the community about a few things. It's a short adventure, maybe leveling up once or twice in the process, starting at level 2/3 probably. D&D 3.5 as the system, four PCs.

The adventure is going to revolve mostly around a wererat cultist trying to restore a petrified Mooncalf to life via obligatory magic ritual. As a result of some things, I had a few questions that I wanted to ask.

Firstly, how dangerous is a Rat Swarm to such low-level PCs? There are two planned encounters with them, and I don't want to accidentally overwhelm them with tougher-than-expected enemies.

Secondly, with the amount of rats they're going to face, eventually most to all of them are going to be infected with Filth Fever and/or Lycanthropy. And while I think a case or two of it would be interesting, I don't want them ALL crippled. Should I just ignore it, or should I reserve it for a "dramatic" moment, sorta?

Also, anyone have any suggestions for a good low-level undead I could use as a boss? I was thinking a Wight, but the negative levels against them would present major issues. I suppose I could take it away and give it another ability, but I was curious to know if anyone had other suggestions.

[polycrac]

Do you know what the characters are playing? A Paladin would give you some nice leeway - partly with dealing with undead (turn from lvl 4, smite before) but also because at lvl 3 they have immunity to normal and magical diseases - you'd have at least one member of the party not taken down by fever or lycanthropy.

As for the choice of undead - perhaps you could use a template (like half vampire - in Libris Mortis) that can be added to another base creature - then you can tweak the level to suit your needs by your choice of base creature.

[keyes2k4]

swarms are more affected by area attacks, so somebody playing a blaster wizard or dragonfire adept will be more effective at fighting such a foe.  Another option is to have the players find some acid flasks or alchemists fires before the encounter, that should ensure that they have a chance against a swarm.

there are tons of good intelligent undead.  A wight would certainly fit the build, or you could go nuts and do a half-vampire wizard or necromancer character literally hell-bent on destroying the party.  Really depending on how much time you want to spend building up this foe you could do many things.

[Amechra]

If you have access to Libris Mortis (The Book of Undead! And bad Latin!), the Necropolitan template is something you can slap on an NPC to make them into an Undead.

It's really just:
- Change their type to Undead.
- Give them Turn Resistance +2.
- Give them +2 on their saves vs. Control Undead.
- They still heal like a living creature, except they swap healing and negative energy spells (so Cure Light Wounds hurts 'em, Inflict Light Wounds heals 'em, etcetera.)

Swarms are a bit tough to deal with unless the party has access to ways to deal with them that aren't contingent on hitting them with big pieces of metal - I'd suggest hinting to people playing melee characters that a torch is more likely to connect with the swarm than their swords or axes would. As long as the spellcasters aren't solely rocking single-target spells (Swarms are immune to them, logically enough), they should be fine on that front.

Now, rat swarms cannot, by the rules, transmit Lycanthropy... however, that's kinda silly, and not AWESOME like turning into rats is. If you want to avoid the whole "LA +2 and extra animal HD harshly affecting the character and what the player wants to do with them" thing (which is a good idea!), may I suggest the following alternate rule?

When a character fails their save against Rat Therianthropy, they gain the Alternate Form (Dire Rat) class feature of the Wererat Savage Progression. While transformed, their alignment shifts to Chaotic Evil and they become an NPC under the DM's control; the player must make a DC 15 Wisdom check to remember anything that happened while they were transformed.

An afflicted character that comes to grips with the fact that they are now a Wererat and works towards controlling their condition may take levels in the Wererat Savage Progression; once they take the first level, their alignment no longer shifts while they are transformed and they no longer require a Wisdom check to remember what happened while they were transformed.

As for Filth Fever... depending on the timescale of the adventure, it might not even be a concern. It takes 1d3 days to show up, and deals 1d3 Dex and Con damage; it'll be gone really quickly with minimal fuss if anyone has any ranks in Heal (1 rank in Heal and a Wisdom of 13 gives you a +2; if you Take 10 while treating a friend with Filth Fever, they will recover in 2 days without taking any ability damage.) Diseases in 3.5 aren't that nasty unless they are supernatural or otherwise especially virulent.