I've beaten him on Hard Classic mode, it wasn't to difficult Only took me 1 attempt after i failed the first time, Just take advantage of Slyade and how he runs to a heal tile when below 50% life after that it is easy, use Warp to warp someone behind desaix and trap him on both sides and just bombard him 1 damage at a time (well 2 since you will double) with all your ranged, repeat win.
