Artax, Hound of Pareus

Flash, Haste, First Strike
When this creature enters the battlefield, if it's
not your turn it gets +0/+4 until end of turn. Otherwise, it gets +4/+0 until end of turn.
Whenever this creature attacks or blocks, choose
hand, library, or graveyard. A random nonland
card in your chosen zone that doesn't have Flash perpetually gains Flash.