Gandalf, the Grey

Reach, Indestructible
Whenever a opponent casts a spell, you may pay {3}{u} and shout "You shall not cast!". Counter that spell. Use this ability only once per turn.
Whenever you counter a spell with Gandalf, the Grey, you may put an experience counter on Gandalf, the Grey.
When Gandalf, the Grey has 5 or more experience counter, transform him.