Downhill Charge

You may sacrifice a Mountain rather than pay this spell's mana cost.
Target creature gets +X/+0 until end of turn, where X is the number of Mountains you control.

Viashino Cutthroat

Haste
At the beginning of the end step, return Viashino Cutthroat to its owner's hand.

Goblin War Buggy

Haste
Echo {1}{R} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)

Keldon Champion

Haste
Echo {2}{R}{R} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Keldon Champion enters, it deals 3 damage to target player or planeswalker.

Mountain

Flametongue Kavu

When Flametongue Kavu enters, it deals 4 damage to target creature.

Raging Goblin

Haste (This creature can attack and {T} as soon as it comes under your control.)

Blazing Salvo

Blazing Salvo deals 3 damage to target creature unless that creature's controller has Blazing Salvo deal 5 damage to them.

Thundering Giant

Shivan Raptor

First strike, haste
Echo {2}{R} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)

Wild Colos

Shock

Arc Lightning

Arc Lightning deals 3 damage divided as you choose among one, two, or three targets.