Rime, Dawnspark Lady

Rime, Dawnspark Lady enters with X +1/+1
counters.
When Rime, Dawnspark Lady attacks, at the beginning of your next precombat main
phase, add an amount of mana in any combination of {g} and/or {u} equal to Rime, Dawnspark Lady's power.
She is both as beautiful and as ferocious as a snowstorm.