Olrich, The Krustallomancer

Whenever a creature you control would die, crystallize it instead. (To crystallize a creature, exile it, then return it to the battlefield under its owner's control face down as an artifact named Crystal. It has "{2}, Sacrifice this artifact: Scry 1.")
As long as you control five or more Crystals, multicolored creatures you control get +2/+2, vigilance, and hexproof.