Yoru, Dimensional Drifter

Flash, Haste, Double strike
When Yoru attacks you may pay {u}{u}. If you do,
create a copy of Yoru. Then, after blockers are
chosen, you must choose either Yoru or the token
to become a 0/1 with 'Tap all creatures blocking
this creature. They don't untap during their
controller's next upkeep.' and 'Sacrifice this
creature at the end of this combat phase'.
If there's a token that is a copy of Yoru after this
combat phase, it becomes a non-token.