Demon Hunters FTW! Damage stack and bonus for Bosses makes it best unit in this game - no game lost in single or multi-player. Only Guardian Summoning can stop them, if you don't believe check my build with 5 Divine Demon Hunters (they're only LVL 25-27, but can fight with Grey Knights lvl 99 without problem): http://www.kongregate.com/games/nerdook/monster-slayers?slayers=197584
Still it makes game unbalanced, rate comment if you find it helpful.
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