[Graeme Dice]

Originally posted by rabelais:
I thought the fatigue was supposed to get divided among the slaves, not reproduced for each.

It is, each slave has their own encumbrance value. The total fatigue cost of the spell is divided between all the communicants and the caster, without any modification for the skill of the caster. The caster has his portion of the fatigue reduced by his skill level bonuses. The total fatigue that each participant receives then has the recipient's spell casting encumbrance added to it.