Mountain

Goblin Guide

Haste
Whenever Goblin Guide attacks, defending player reveals the top card of their library. If it's a land card, that player puts it into their hand.

Mutagenic Growth

({G/P} can be paid with either {G} or 2 life.)
Target creature gets +2/+2 until end of turn.

Soul-Scar Mage

Prowess
If a source you control would deal noncombat damage to a creature an opponent controls, put that many -1/-1 counters on that creature instead.

Lava Spike

Lava Spike deals 3 damage to target player or planeswalker.

Lava Dart

Lava Dart deals 1 damage to any target.
Flashback—Sacrifice a Mountain. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Furnace Scamp

Whenever Furnace Scamp deals combat damage to a player, you may sacrifice it. If you do, Furnace Scamp deals 3 damage to that player.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Mana Clash

You and target opponent each flip a coin. Mana Clash deals 1 damage to each player whose coin comes up tails. Repeat this process until both players' coins come up heads on the same flip.

Monastery Swiftspear

Haste
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)

Fossil Find

Return a card at random from your graveyard to your hand, then reorder your graveyard as you choose.

Play with Fire

Play with Fire deals 2 damage to any target. If a player is dealt damage this way, scry 1. (Look at the top card of your library. You may put that card on the bottom.)