Mei, Hopeful Climatologist

Ultimate: Blizzard - (Mei, Hopeful Climatologist enters the battlefield with three charge counters on her. At the beginning of your upkeep, remove a charge counter, then, when the last is removed, tap up to three target creatures, they don't untap during their owners next untap step, then place three charge counters on Mei.)
{w}{u}, {t}: Ice Wall (Target creature can't attack this turn)