Cliff Threader

Mountainwalk (This creature can't be blocked as long as defending player controls a Mountain.)

Goblin Mountaineer

Sanctimony

Whenever an opponent taps a Mountain for mana, you may gain 1 life.

Volcanic Strength

Enchant creature
Enchanted creature gets +2/+2 and has mountainwalk. (It can't be blocked as long as defending player controls a Mountain.)

Mountain

Peak Eruption

Destroy target Mountain. Peak Eruption deals 3 damage to that land's controller.

Blood Moon

Plains

Goblin Spelunkers

Magus of the Moon

Ragavan, Nimble Pilferer

Whenever Ragavan, Nimble Pilferer deals combat damage to a player, create a Treasure token and exile the top card of that player's library. Until end of turn, you may cast that card.
Dash {1}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)