Exoskeletal Armor

Enchant creature
Enchanted creature gets +X/+X, where X is the number of creature cards in all graveyards.

Possessed Centaur

Trample
Threshold — As long as seven or more cards are in your graveyard, Possessed Centaur gets +1/+1, is black, and has "{2}{B}, {T}: Destroy target green creature."

Basking Rootwalla

{1}{G}: Basking Rootwalla gets +2/+2 until end of turn. Activate only once each turn.
Madness {0} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Wild Mongrel

Discard a card: Wild Mongrel gets +1/+1 and becomes the color of your choice until end of turn.

Elephant Guide

Enchant creature
Enchanted creature gets +3/+3.
When enchanted creature dies, create a 3/3 green Elephant creature token.

Cadaverous Knight

Flanking (Whenever a creature without flanking blocks this creature, the blocking creature gets -1/-1 until end of turn.)
{1}{B}{B}: Regenerate Cadaverous Knight.

Might of Oaks

Target creature gets +7/+7 until end of turn.

Wall of Shadows

Defender (This creature can't attack.)
Prevent all damage that would be dealt to Wall of Shadows by creatures it's blocking.
Wall of Shadows can't be the target of spells that can target only Walls or of abilities that can target only Walls.

Unholy Strength

Enchant creature
Enchanted creature gets +2/+1.

Sylvan Might

Target creature gets +2/+2 and gains trample until end of turn.
Flashback {2}{G}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)