Lightning Strike

Lightning Strike deals 3 damage to any target.

Mountain

Burning-Tree Emissary

When Burning-Tree Emissary enters, add {R}{G}.

Rakdos Cackler

Unleash (You may have this creature enter with a +1/+1 counter on it. It can't block as long as it has a +1/+1 counter on it.)

Goblin Rabblemaster

Other Goblin creatures you control attack each combat if able.
At the beginning of combat on your turn, create a 1/1 red Goblin creature token with haste.
Whenever Goblin Rabblemaster attacks, it gets +1/+0 until end of turn for each other attacking Goblin.

Firefist Striker

Battalion — Whenever Firefist Striker and at least two other creatures attack, target creature can't block this turn.

Foundry Street Denizen

Whenever another red creature you control enters, Foundry Street Denizen gets +1/+0 until end of turn.

Mutavault

{T}: Add {C}.
{1}: Mutavault becomes a 2/2 creature with all creature types until end of turn. It's still a land.

Ash Zealot

First strike, haste
Whenever a player casts a spell from a graveyard, Ash Zealot deals 3 damage to that player.

Stoke the Flames

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Stoke the Flames deals 4 damage to any target.

Rubblebelt Maaka

Bloodrush — {R}, Discard Rubblebelt Maaka: Target attacking creature gets +3/+3 until end of turn.

Firedrinker Satyr

Whenever Firedrinker Satyr is dealt damage, it deals that much damage to you.
{1}{R}: Firedrinker Satyr gets +1/+0 until end of turn and deals 1 damage to you.