Aokiji Kuzan, The Relentless

Whenever you untap a nonland permanent
you control, put a frost counter on target
permanent an opponent controls.
(Tap each nonland permanent with a frost
counter on it. Each nonland permanent with a
frost counter on it doesn't untap during its
controllers untap step. At the beginning of your
precombat main phase, remove all frost counters
from permanents.)