Wall of Heat

Wall of Granite

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Valakut, the Molten Pinnacle

Valakut, the Molten Pinnacle enters tapped.
Whenever a Mountain you control enters, if you control at least five other Mountains, you may have Valakut, the Molten Pinnacle deal 3 damage to any target.
{T}: Add {R}.

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Wall of Dust

Defender (This creature can't attack.)
Whenever Wall of Dust blocks a creature, that creature can't attack during its controller's next turn.

Wall of Stone

Mountain

Insurrection

Untap all creatures and gain control of them until end of turn. They gain haste until end of turn.

Wall of Lava

Defender (This creature can't attack.)
{R}: Wall of Lava gets +1/+1 until end of turn.

Koth, Fire of Resistance

+2: Search your library for a basic Mountain card, reveal it, put it into your hand, then shuffle.
−3: Koth, Fire of Resistance deals damage to target creature equal to the number of Mountains you control.
−7: You get an emblem with "Whenever a Mountain you control enters, this emblem deals 4 damage to any target."

Aether Membrane

Defender; reach (This creature can block creatures with flying.)
Whenever Aether Membrane blocks a creature, return that creature to its owner's hand at end of combat.