Goblin King

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

Volcanic Dragon

Scorching Missile

Scorching Missile deals 4 damage to target player or planeswalker.
Flashback {9}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Raging Goblin

Haste (This creature can attack and {T} as soon as it comes under your control.)

Mountain

Engulfing Flames

Engulfing Flames deals 1 damage to target creature. It can't be regenerated this turn.
Flashback {3}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Magma Giant

When Magma Giant enters, it deals 2 damage to each creature and each player.

Threaten

Untap target creature and gain control of it until end of turn. That creature gains haste until end of turn. (It can attack and {T} this turn.)

Reckless Charge

Target creature gets +3/+0 and gains haste until end of turn.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Chandra's Magmutt

{T}: Chandra's Magmutt deals 1 damage to target player or planeswalker.

Retromancer

Whenever Retromancer becomes the target of a spell or ability, Retromancer deals 3 damage to that spell or ability's controller.