Amazing
I would really want to find thorns there as well - if you get any, you will easily do all tasks, including the school of gloom's task, because thorns own any boss up until the Driller and Gremlion. I have a feeling that thorns + stone skin + magic spring + adrenaline + occasional haste spell will actually kill the driller easily as well.
Great setup - that troop setup makes for even easier win that I wrote.