[Sombre]

A major issue with domsummon is that there are only 3 strengths - domsummon 1 produces a LOT of guys. I think it's actually 1 per point of dominion, give or take. Domsummon 2 produces half of a LOT, so if you're in dom 10 for instance (which is extreme, admittedly), you're talking something like 5 a turn. So with three Slann, not a crazy number at all in the early game, you'd be getting 15 free temple guard every turn. Then there's domsummon 20, which is 20 times less than domsummon 1. That's what the vampire queen has for summong vampires, for instance - you get one very occasionally in very strong dominion.