Kozue, Elusive Vaporblade

Ninjutsu {u}{u}
Discard a card: Exile Kozue. Return it to battlefield under your control at the beginning
of the next end step. If Kozue was attacking, you
may return it to the battlefield after blockers
have been declared, tapped and unblocked and attacking the same player or planeswalker.
When Kozue enters the battlefield, you may put
target instant or sorcery card from your
graveyard on top of your library.