Economically, you can crush them with any castle... you just need to know how (and that's the whole problem:D)... but if you play as demons, you can teleport archers away (special ability of archdemons + surprise attack) or charm them with succubi (it's generally better to charm nearby ents if you have enough mana:D), although I don't really like playing as alt-demons (I have a feeling I'll like it soon)... and still, it's better against elves... I don't know about other races... only if using spells.
Added after 10 minutes
By the way... I just played as elves and I liked the trio of druid-wolf rider + wild ents + hero with expert light magic... in short:
in the final battle, it was intense... in general, the druids created a channel, the next turn the hero casts mass haste.... then the ents move - I skip the turn, using the rage ability.... then the druids cast stone skin, and the ents turned into a killing machine...