Azla Darkcoil, Drowned-Lord

Whenever you cast an instant or sorcery spell,
target player mills X cards, where X is that spell's converted mana cost. If one or more
creature cards are milled this way, create a
tapped 2/2 black Zombie creature token.
Tap X untapped Zombies and/or Wizards you
control: Cast target instant or sorcery in your graveyard with converted mana cost X or less
without paying it's mana cost. Then, exile it.