2 solutions just came up with
to counter communion(only works if he does not have a staff of storms on a commander or if he casts storm).
one of the costs 30 bloodslaves and 5 fire gems.
the other one costs 5 wind gems and 5 fire gems.
and you need construction 6 and either bloodmagic or conjuration magic research.
guaranteed to kill pretty much anything almost.
(i'm leaving the details for everyone to figure out
)