Borealis, the Freezing Fog

Flying, vigilance

Whenever you tap a nonland permanent for mana, add {s}.

Whenever a snow creature you control deals combat damage to a player, you may put a stun counter on up to one other nonland permanent an opponent controls.

{s}{u}{g}, {t}: Draw a card for each stun counter among permanents. Snow creatures you control gain trample until end of turn.