Temporal Decay

Put two Time Counters on or remove two
Time Counters from target permanent.
Purity {u} - Tap another target creature. It
doesn't untap during its controller's next untap
step.
Purity {b} - Destroy target creature with power
2 or less.
(When this card is cast, if its cost was paid using
mana of only one color, activate the Purity effect of
the color of mana spent.)