Hi!
  OK, so I have the 1 vs 1 conflict rules set and tested. Its a tweak on Otherkind. It works the way I want it to and the numbers are solid. to summarize:
  Each char has a stat for Ambition, Cunning and Vigilance. When there is a conflict, players set their goals (intentions) and then roll three dice each. Then after the roll, they assign one dice each to Ambition, Cunning and Vigilance. Then each player compares Ambition Dice + Ambition Stat vs each other. the higher of the two gets points towards their goal. Also, one player adds Cunning stat to their Cunning die and compares against their opponents Vigilance Die + Stat. If the Cunning total is higher, the difference is the Harm inflicted. Skills let you add +1 to a die, powers give you a bonus die.

  The trick is, this works great. But it is sort of hard wired for one on one conflict.

  So, there are a couple of ways I can handle one vs many:
1) Single player rolls once and compares against many
Pros: Feels like the players can use team work. Less admin.
Cons: Seems like good/bad rolls would have too dramatic of an affect.

2) Single player rolls separately against each of many players:
Pros: Feels like the is too powerful. One bad/good roll doesn;t skew the whole fight
Cons: more dice/numbers/admin.

3) Single player rolls once, one of the many players roll and the rest give bonuses to them.

  So, this game is supposed to be heroic steam punk with Vampires and a hardcore dystopic setting. Typically, one Vampire will be facing down a group of PCs. Which one of these do you think sets the tone best. My guts says to go with #3, is there something you see that makes that a less than optimal idea?

All,
  OK, the mechanic has to cover 4 combinations:
1) 1 vs 1 - Done, tested, good
2) 1 NPC vs Many PCs - My original question
3) 1 PC vs Many NPCs
4) Many NPCs vs Many PCs

  My design goals are (in no particular order):
a) Simple system, not too complex
b) Short conflicts (3-5 Rounds)
c) Reward Teamwork
d) Prevent no-win situations
e) Reward Strategy and Tactics (I have this on 1 vs 1 and I want that to carry forward)
f) Provide flexibility for the players

  The only problems I have with Option 1, really, are:
1) Extremely high/low rolls can break B and D
2) Can break F if the player on the "one character" side of a one vs many character conflict does not want to harm all the opposing characters equally.

  Also, what Goal is each player rolling for in a multilayer conflict? And does the player on the "one character" side of a conflict get to create a separate goal for each character they are rolling against, or do they just have one overarching goal?
Dave M