Against which factions is it easier for demons to fight, and against which is it more difficult?

Considering that the ballista of the Mages is very powerful (unlike the Necromancers, Dwarves, or Fortress faction))), the situation looks bleak.

I don't know, I wouldn't say that Hafik has such a strong ballista. In my opinion, Daleb or Viti have much stronger ones. Gremlins + punishing strike and mages are much more of a concern.