A couple of notes for actual play:
--Not all field effects are created equal. Something that goes off at the end of the turn will keep adding up if you don't nuke it, something that goes off at the start of the turn is useless if you can just kill everything they drop instead.
--Similarly, don't just pop your special abilities when their cooldown comes up, but don't be afraid to use them either. Holding archers until after they've done their shock can be good, but not if a single turn of those guys would help you clear a field.
--Always look for lethal. This game can be very swingy, particularly with a couple of the elites (11dmg and gives a random ally double attack for example). Sometimes you're better off putting a wall in front of their attacks, but sometimes you can go around the side for a win. I've had quite a few battles where my opponent decided to kill dudes instead of hit face, and so lets me live at a couple of HP and drop my own bomb.
--Despite all that, sometimes you just run into something you can't handle. It happens, this is a whale game, not worth tilting over.