Mountain

Borderland Marauder

Whenever this creature attacks, it gets +2/+0 until end of turn.

Flameheart Werewolf

Whenever this creature blocks or becomes blocked by a creature, this creature deals 2 damage to that creature.
At the beginning of each upkeep, if a player cast two or more spells last turn, transform this creature.

Kessig Forgemaster

Whenever this creature blocks or becomes blocked by a creature, this creature deals 1 damage to that creature.
At the beginning of each upkeep, if no spells were cast last turn, transform this creature.

Kessig Forgemaster // Flameheart Werewolf

Stonewright

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as Stonewright is paired with another creature, each of those creatures has "{R}: This creature gets +1/+0 until end of turn."

Neck Breaker

Attacking creatures you control get +1/+0 and have trample.
At the beginning of each upkeep, if a player cast two or more spells last turn, transform this creature.

Breakneck Rider

At the beginning of each upkeep, if no spells were cast last turn, transform this creature.

Breakneck Rider // Neck Breaker

Outnumber

Outnumber deals damage to target creature equal to the number of creatures you control.

Deem Worthy

Deem Worthy deals 7 damage to target creature.
Cycling {3}{R} ({3}{R}, Discard this card: Draw a card.)
When you cycle this card, you may have it deal 2 damage to target creature.

Thriving Bluff

This land enters tapped. As it enters, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

Riot Ringleader

Whenever this creature attacks, Human creatures you control get +1/+0 until end of turn.

Kessig Malcontents

When this creature enters, it deals damage to target player or planeswalker equal to the number of Humans you control.

Titan of Eternal Fire

Each Human creature you control has "{R}, {T}: This creature deals 1 damage to any target."

Slaying Fire

Slaying Fire deals 3 damage to any target.
Adamant — If at least three red mana was spent to cast this spell, it deals 4 damage instead.

Hanweir Garrison

Whenever this creature attacks, create two 1/1 red Human creature tokens that are tapped and attacking.
(Melds with Hanweir Battlements.)

Lightning Mauler

Soulbond (You may pair this creature with another unpaired creature when either enters. They remain paired for as long as you control both of them.)
As long as this creature is paired with another creature, both creatures have haste.