Crystal

I don't remember exactly, it was a long time ago, but I think in the first week I cleared out the monsters at the top, took the Artifact of Despair, and a shield that gives +4 to everything, and also leveled up Expert Earth. In the second week, I attacked the horde of dendroids at the bottom with a horde of gremlins (with a few golems and gargoyles) :) Although there might have been a few more mages.