Taigam, Ojutai Master

Prowess 3 (Whenever you cast a noncreature spell, this creature gets +3/+3 until end of turn.)
Whenever you cast a noncreature spell, put a mastery counter on another target creature.
Creatures with mastery counters on them have Prowess 3.
Taigam is Ojutai's second, teaching in the Dragon's absence and learning in his presence.