Zhur-Taa Druid

{T}: Add {G}.
Whenever you tap Zhur-Taa Druid for mana, it deals 1 damage to each opponent.

Mountain

Apocalypse Hydra

Apocalypse Hydra 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 Apocalypse Hydra: It deals 1 damage to any target.

Ghor-Clan Rampager

Trample
Bloodrush — {R}{G}, Discard Ghor-Clan Rampager: Target attacking creature gets +4/+4 and gains trample until end of turn.

Mizzium Mortars

Mizzium Mortars deals 4 damage to target creature you don't control.
Overload {3}{R}{R}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Savage Ventmaw

Flying
Whenever Savage Ventmaw attacks, add {R}{R}{R}{G}{G}{G}. Until end of turn, you don't lose this mana as steps and phases end.

Rootbound Crag

Rootbound Crag enters tapped unless you control a Mountain or a Forest.
{T}: Add {R} or {G}.

Forest

Managorger Hydra

Trample
Whenever a player casts a spell, put a +1/+1 counter on Managorger Hydra.

Grand Warlord Radha

Haste
Whenever one or more creatures you control attack, add that much mana in any combination of {R} and/or {G}. Until end of turn, you don't lose this mana as steps and phases end.

Taiga

Burning-Tree Emissary

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

Llanowar Elves

Stomping Ground

({T}: Add {R} or {G}.)
As Stomping Ground enters, you may pay 2 life. If you don't, it enters tapped.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Wooded Foothills

{T}, Pay 1 life, Sacrifice Wooded Foothills: Search your library for a Mountain or Forest card, put it onto the battlefield, then shuffle.

Ruric Thar, the Unbowed

Vigilance, reach
Ruric Thar, the Unbowed attacks each combat if able.
Whenever a player casts a noncreature spell, Ruric Thar deals 6 damage to that player.