Rootbound Crag

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

Embercleave

Flash
This spell costs {1} less to cast for each attacking creature you control.
When Embercleave enters, attach it to target creature you control.
Equipped creature gets +1/+1 and has double strike and trample.
Equip {3}

Fervent Champion

First strike, haste
Whenever Fervent Champion attacks, another target attacking Knight you control gets +1/+0 until end of turn.
Equip abilities you activate that target Fervent Champion cost {3} less to activate.

Game Trail

As Game Trail enters, you may reveal a Mountain or Forest card from your hand. If you don't, Game Trail enters tapped.
{T}: Add {R} or {G}.

Goblin Piledriver

Protection from blue (This creature can't be blocked, targeted, dealt damage, or enchanted by anything blue.)
Whenever Goblin Piledriver attacks, it gets +2/+0 until end of turn for each other attacking Goblin.

Temur Battle Rage

Target creature gains double strike until end of turn.
Ferocious — That creature also gains trample until end of turn if you control a creature with power 4 or greater.

Timbercrown Pathway

Cragcrown Pathway

Cragcrown Pathway // Timbercrown Pathway

Stomping Ground

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

Forest

Mountain

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.

Heart's Desire

Create a 1/1 white Human creature token. (Then exile this card. You may cast the creature later from exile.)

Lovestruck Beast

Lovestruck Beast can't attack unless you control a 1/1 creature.

Lovestruck Beast // Heart's Desire

Burning-Tree Emissary

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

Den of the Bugbear

If you control two or more other lands, Den of the Bugbear enters tapped.
{T}: Add {R}.
{3}{R}: Until end of turn, Den of the Bugbear becomes a 3/2 red Goblin creature with "Whenever this creature attacks, create a 1/1 red Goblin creature token that's tapped and attacking." It's still a land.