Bayou Groff

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

Llanowar Elves

Shock

Apocalypse Hydra

This creature enters with X +1/+1 counters on it. If X is 5 or more, it enters with an additional X +1/+1 counters on it.
{1}{R}, Remove a +1/+1 counter from this creature: It deals 1 damage to any target.

Burning-Tree Emissary

Domri, Anarch of Bolas

Creatures you control get +1/+0.
+1: Add {R} or {G}. Creature spells you cast this turn can't be countered.
−2: Target creature you control fights target creature you don't control.

Ruby, Daring Tracker

Haste (This creature can attack and {T} as soon as it comes under your control.)
Whenever Ruby attacks while you control a creature with power 4 or greater, Ruby gets +2/+2 until end of turn.
{T}: Add {R} or {G}.

Agent of Stromgald

Forest

Claim the Firstborn

Gain control of target creature with mana value 3 or less until end of turn. Untap that creature. It gains haste until end of turn.

Dragon Sniper

Cartouche of Zeal

Enchant creature you control
When this Aura enters, target creature can't block this turn.
Enchanted creature gets +1/+1 and has haste. (It can attack and {T} no matter when it came under your control.)

Mountain

Fleeting Effigy

Haste
At the beginning of your end step, return this creature to its owner's hand. (Return it only if it's on the battlefield.)
{2}{R}: This creature gets +2/+0 until end of turn.

Savage Mansion

This land enters tapped.
{T}: Add {R} or {G}.
{4}, {T}: Surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Fanatical Firebrand

Haste (This creature can attack and {T} as soon as it comes under your control.)
{T}, Sacrifice this creature: It deals 1 damage to any target.