One thing that drives me nuts is when an enemy with a ranged attack, especially Gremlin Healers, go and hide in brambles or spikes so that I have to take a bunch of unavoidable damage to go deal with them, less they keep using Heal: Target on bunch of gremlins I'm trying to kill.
Even if they didn't take damage, at least program them not to camp in areas we have to take damage to walk through.