Koth, Fire of Resistance

+2: Search your library for a basic Mountain card, reveal it, put it into your hand, then shuffle.
−3: Koth, Fire of Resistance deals damage to target creature equal to the number of Mountains you control.
−7: You get an emblem with "Whenever a Mountain you control enters, this emblem deals 4 damage to any target."

Goblin Instigator

When Goblin Instigator enters, create a 1/1 red Goblin creature token.

Fiery Emancipation

If a source you control would deal damage to a permanent or player, it deals triple that damage to that permanent or player instead.

Innocent Bystander

Whenever Innocent Bystander is dealt 3 or more damage, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Goblin Assailant

Mana Flare

Whenever a player taps a land for mana, that player adds one mana of any type that land produced.

Battle-Scarred Goblin

Whenever Battle-Scarred Goblin becomes blocked, it deals 1 damage to each creature blocking it.

Goblin Blast-Runner

Goblin Blast-Runner gets +2/+0 and has menace as long as you sacrificed a permanent this turn.

Enterprising Scallywag

At the beginning of your end step, if you descended this turn, create a Treasure token. (You descended if a permanent card was put into your graveyard from anywhere.)

Goblin Locksmith

Whenever Goblin Locksmith attacks, creatures with defender can't block this turn.

Fugitive Codebreaker

Prowess, haste
Disguise {5}{R}. This cost is reduced by {1} for each instant and sorcery card in your graveyard. (You may cast this card face down for {3} as a 2/2 creature with ward {2}. Turn it face up any time for its disguise cost.)
When Fugitive Codebreaker is turned face up, discard your hand, then draw three cards.

Raid Bombardment

Whenever a creature you control with power 2 or less attacks, Raid Bombardment deals 1 damage to the player or planeswalker that creature is attacking.

Krenko, Mob Boss

{T}: Create X 1/1 red Goblin creature tokens, where X is the number of Goblins you control.