Valentina, Cunning Scout

First strike, Lifelink
At the beginning of your end step, if Valentina, Cunning Scout entered the battlefield this turn,
she phases out.
Whenever Valentina, Cunning Scout attacks,
you may pay {u/r}{u/r}. If you do, exile the top two
cards of target opponent's library face down. You
may look at and play those cards for as long as
they remain exiled.