How much should I hurt my PCs' opponent party?

[Ologath]

Okay, so some quick background here:

I'm running a homebrew campaign and the four, 8th level PCs are working with four 8th level evil NPCs to work though a dragon's lair in order to get an artifact that both parties want.

The two groups recently split because, (a) they were getting on each other's nerves and (b) combat was taking way too long to run. As soon as the two parties went their own ways (still with the same goals) the PCs started talking about killing the other party after they'd taken out the dragon. Not unexpected. Here comes the problem.

Since that time, the PCs have run across a couple of encounters and thus spent resources such as HP, spells, wand charges, etc. My question is, how many resources should I take from the evil party (who have also hit a few encounters), knowing that they will fight the PCs? I want this to be a somewhat even fight.

Thanks in advance for any advice.

[Corrik]

I would just roll for it. d20 for percentage of health, d4 or d6 for abilities used, d8 or d10 for spells used, etc. Obviously your numbers depends on the number and difficulty of the encounters and traps that the evil party has dealt with but you get the general idea.

[Chobemaster]

That's not "mechanically" answerable without knowing what the other encounters the evil NPC's have theoretically overcome.

If you assume that their path was equally difficult as the PCs', then they should be roughly as-depleted as the PCs are, unless your PCs are big into over-kill, using their best remaining spell on a wounded goblin.

You have 3 real choices, IMO.

1. run the NPCs through the encounters and see what happens. This is time consuming but if you do a good job, is the most realistic approach.

2. Evaluate the paths each party has taken, and whether or not your PCs were above/below average performance in their encounters. If the paths are the same, and your PCs did an average job in how they approached them, presumably the NPCs also did an average job and they should be in the same shape the PCs are. If the PCs went the hard way, then they should be more beaten up than the NPCs. Most especially, note that if the paths were the same except that the PCs faced a meaningful-challenge dragon and the NPCs did not, the NPCs ought to be way ahead of the PCs and it's probably a TPK, which it should be. This is what I would do.

3. Decide that you want an even fight and make it so. This will be dependent on how the PCs are at the start of the big battle, so we can't answer it in advance here.

[Andostre]

Well, they're evil characters, so would that give any extra moral freedom in how they handle their encounters? I realize that in a dungeon, almost all parties fight dirty and use what advantage they can, but maybe the evil party has the same thoughts about killing the PCs, so they're looking for any advantage they can find to bring that about? I'm envisioning the evil party finding a way to negotiate with a band of kobolds, or something. "If you help us kill this other party, you can have any treasure found on them!"

Of course, being an evil party, they might just kill the kobolds when they're done. Of course, being kobolds, they might just decide to try and kill both parties in the middle of the fight! I'm probably just making this more complicated.

[Gnomezrule]

None.

The evil party since splitting up has only appeared to take a divergent path but instead is following using stealth and/or scrying if they have access. This info will be used to strike at the opportune moment. Or they are simply re-arming or setting additional traps for the parties march out of the lair after they have already taken out the dragon/retrieved the artifact. If such shennagins are not possible I would run the NPC's through the challenges they faced on paper and deplete logical rescources.

[DrDeth]

Quite a bit. You see, NPC can always Nova, they never have to save for the next encounter. I’d have them down at least what the PC party is.