Forest

Hunger of the Howlpack

Put a +1/+1 counter on target creature.
Morbid — Put three +1/+1 counters on that creature instead if a creature died this turn.

Bayou Groff

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

Quirion Ranger

Return a Forest you control to its owner's hand: Untap target creature. Activate only once each turn.

Nettle Sentinel

Nettle Sentinel doesn't untap during your untap step.
Whenever you cast a green spell, you may untap Nettle Sentinel.

Nest Invader

When Nest Invader enters, create a 0/1 colorless Eldrazi Spawn creature token. It has "Sacrifice this creature: Add {C}."

Young Wolf

Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)

Rancor

Enchant creature
Enchanted creature gets +2/+0 and has trample.
When Rancor is put into a graveyard from the battlefield, return Rancor to its owner's hand.

Voracious Varmint

Vigilance
{1}, Sacrifice Voracious Varmint: Destroy target artifact or enchantment.

Skarrgan Pit-Skulk

Bloodthirst 1 (If an opponent was dealt damage this turn, this creature enters with a +1/+1 counter on it.)
Creatures with power less than Skarrgan Pit-Skulk's power can't block it.

Vines of Vastwood

Kicker {G} (You may pay an additional {G} as you cast this spell.)
Target creature can't be the target of spells or abilities your opponents control this turn. If this spell was kicked, that creature gets +4/+4 until end of turn.

Savage Swipe

Target creature you control gets +2/+2 until end of turn if its power is 2. Then it fights target creature you don't control. (Each deals damage equal to its power to the other.)