Enchant creature Enchanted creature can't attack or block. When enchanted creature becomes the target of a spell or ability, exile that creature.
Official Rulings for Crystallization
5/1/2009 : When the enchanted creature becomes the target of a spell or ability, Crystallization's last ability will trigger. When that ability resolves, that creature will be exiled, even if Crystallization has left the battlefield or is enchanting a different creature by that time. If Crystallization is still enchanting the same creature, Crystallization will then be put into its owner's graveyard as a state-based action.