Raven, Prophetess of Disaster

Prophecy 2 (When this creature enters the battlefield, put 2 time counters on it. At the beginning of your end step, remove a time counter from this creature. If there are no time counters
on this creature, it's prophecy is realized.)
When Raven's prophecy is realized, destroy
all creatures you don't control. They can't
be regenerated.