ashiok's dark oath

when ashiok's oath enters the battlefield, target players mill 4 cards and you can exile up to 3 cards
from any graveyard, you can cast the exiled
cards that way for their cost paying any mana
color.
any player can use surveil 2 if he does he gains
2 madness counters and you create a 2/3 black
and blue nightmare with" when that card
bloequar or attacks the opponent exiles 2 cards.
"you can play any card exiled by ashiok's dark
oath