When the wizard in the spot; (AKA: The third one!) in a duel casts polymorph treant, and the enemy in the spot (AKA: The first one!) happens to be a model equal to, or smaller than Deep Warren's Angler Thug, It is impossible to select that enemy for any spell that requires the selection of a single target because the treant's selection box is too tall.
Please fix this problem as it is a game ruin-er for me. Mainly because unless someone has an AOE spell, (Example: Meteor Strike, Blizzard, Scarecrow, Exc...) all wizards in that current duel; Even the polymorphed wizard; Cannot target the enemy spot.
Not a fix, but a possible work around for you. Go to your Gameplay Options menu in game and turn 2D Combat Display to Yes. It will then list all your opponents across the top of screen so you can click those name boxes instead of the spot in the battle circle.
spot; (AKA: The third one!) in a duel casts polymorph treant, and the enemy in the 
spot (AKA: The first one!) happens to be a model equal to, or smaller than Deep Warren's Angler Thug, It is impossible to select that enemy for any spell that requires the selection of a single target because the treant's selection box is too tall.
Meteor Strike, 
Blizzard, 
Scarecrow, Exc...) all wizards in that current duel; Even the polymorphed wizard; Cannot target the 