Rodricka, Spirit Tuner

{t}: Add {w} or {u}. Spend this mana only to cast a Spirit spell or activate an ability of a Spirit or Spirit card.
Whenever a nontoken Spirit enters the battlefield under your control, you get and experience counter. This ability only triggers once each turn.
At the beginning of combat on your turn, put X +1/+1 counters on target Spirit you control, where X is the number of experience counters you have. It gains vigilance until end of turn.