soul drain

[thejeff]

It's a battlefield enchantment, not a caster only spell, so the communion slaves won't get anything from it, other than casting fatigue.
Only one per side in a battle.

Only the main path is counted for fatigue, so the slaves lack of death doesn't matter.

All of that is theoretical, I haven't tested that particular setup and Dominions surprises me regularly, but that's how it should behave.