[zzcat]

MaxWilson said:
3. The short answer is that fatigue is split between master/slaves BEFORE adjusting for path levels, but slaves also get the communion bonus to their paths for these purposes. If a spell is cast which requires D4 and 400 fatigue, and there are 4 slaves in the communion all with no Death paths, each slave and the master will take 80 fatigue, adjusted for path levels and drain (plus fatigue, for the master). With the +2 communion bonus for 4 slaves, each slave is D2 casting a D4 spell, and since they are 2 levels short they take triple fatigue damage or 240 fatigue (which I think means 40 fatigue gets converted to 4 HP damage). If you are N levels short you take (N+1) times fatigue, if you are N levels over you take 1/(N+1) times fatigue.

Does it help if the master spends addtional gems? In this case, using 2 more D gems to reduce 160 fatigue for each slave seems very cost-effective.