Kronya, Shifting Assassin

You may have Kronya, Shifting Assassin
enter the battlefield as a copy of any
creature on the battlefield, except it has
vanishing 3 if that creature doesn't
have vanishing.
(A permanent with vanishing 3 enters the battlefield
with three time counters on it. At the beginning of
your upkeep, remove a time counter from it. When the
last is removed, sacrifice it.)