As long as there are four or more creature cards in your graveyard, Gray Slaad has menace (This creature can't be blocked except by two or more creatures.) and deathtouch (Any amount of damage this deals to a creature is enough to destroy it.).
4/1
Entropic Decay
Sorcery — Adventure
Mill (To mill a card, a player puts the top card of their library into their graveyard.) four cards. (Then exile this card. You may cast the creature later from exile.)