Gauntlet of Might

Red creatures get +1/+1.
Whenever a Mountain is tapped for mana, its controller adds an additional {R}.

Mox Ruby

Goblin King

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

Sol Ring

Goblin Balloon Brigade

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

Mountain

Uthden Troll

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Mons's Goblin Raiders

Black Lotus

{T}, Sacrifice Black Lotus: Add three mana of any one color.

Fire Elemental

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.

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.