Fireball

This spell costs {1} more to cast for each target beyond the first.
Fireball deals X damage divided evenly, rounded down, among any number of targets.

Mountain

Mons's Goblin Raiders

Manabarbs

Whenever a player taps a land for mana, Manabarbs deals 1 damage to that player.

Goblin King

Other Goblins get +1/+1 and have mountainwalk.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Disintegrate

Disintegrate deals X damage to any target. If it's a creature, it can't be regenerated this turn, and if it would die this turn, exile it instead.

Goblin Balloon Brigade

{R}: Goblin Balloon Brigade gains flying until end of turn.