Entropic Decay

Mill four cards. (Then exile this card. You may cast the creature later from exile.)

Gray Slaad

As long as there are four or more creature cards in your graveyard, Gray Slaad has menace and deathtouch.

Gray Slaad // Entropic Decay

Myconid Spore Tender

Infesting Spores — When Myconid Spore Tender enters, destroy up to one target artifact or enchantment.

Loathsome Chimera

Escape—{4}{G}, Exile three other cards from your graveyard. (You may cast this card from your graveyard for its escape cost.)
Loathsome Chimera escapes with a +1/+1 counter on it.

Bayou Groff

As an additional cost to cast this spell, sacrifice a creature or pay {3}.

Crowned Ceratok

Trample
Each creature you control with a +1/+1 counter on it has trample.

Young Deathclaws

Menace (This creature can't be blocked except by two or more creatures.)
Each creature card in your graveyard has scavenge. The scavenge cost is equal to its mana cost. (Exile a creature card from your graveyard and pay its mana cost: Put a number of +1/+1 counters equal to that card's power on target creature. Scavenge only as a sorcery.)