[archaeolept]

ehh, so you lose a few communicants. there are more where those came from.

but really there are only two things to do:
1. as huzurdaddi said, get mages capable of casting relief (lizards are best, but druids w/ a nature staff work just fine)
2. up your ratio of communicants to theurgs, and go in w/ a stronger army (thus a shorter combat).

for mictlan, one word only: Devils.