Lava Axe

Lava Axe deals 5 damage to target player or planeswalker.

Cone of Flame

Cone of Flame deals 1 damage to any target, 2 damage to another target, and 3 damage to a third target.

Foundry Street Denizen

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

Furnace Whelp

Flying
{R}: Furnace Whelp gets +1/+0 until end of turn.

Shivan Dragon

Flying
{R}: This creature gets +1/+0 until end of turn.

Lightning Strike

Lightning Strike deals 3 damage to any target.

Thundering Giant

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

Goblin Roughrider

Rummaging Goblin

Paragon of Fierce Defiance

Other red creatures you control get +1/+1.
{R}, {T}: Another target red creature you control gains haste until end of turn. (It can attack and {T} this turn.)

Staff of the Flame Magus

Whenever you cast a red spell or a Mountain you control enters, you gain 1 life.

Borderland Marauder

Whenever Borderland Marauder attacks, it gets +2/+0 until end of turn.

Seismic Strike

Seismic Strike deals damage to target creature equal to the number of Mountains you control.