Krenko, Mob Boss

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

Petravark

When Petravark enters, exile target land.
When Petravark leaves the battlefield, return the exiled card to the battlefield under its owner's control.

Ore-Scale Guardian

This spell costs {1} less to cast for each land card in your graveyard.
Flying, haste

Akki Raider

Whenever a land is put into a graveyard from the battlefield, Akki Raider gets +1/+0 until end of turn.

Cavalier of Flame

{1}{R}: Creatures you control get +1/+0 and gain haste until end of turn.
When Cavalier of Flame enters, discard any number of cards, then draw that many cards.
When Cavalier of Flame dies, it deals X damage to each opponent and each planeswalker they control, where X is the number of land cards in your graveyard.

Ib Halfheart, Goblin Tactician

Whenever another Goblin you control becomes blocked, sacrifice it. If you do, it deals 4 damage to each creature blocking it.
Sacrifice two Mountains: Create two 1/1 red Goblin creature tokens.

Goblin Fire Fiend

Haste
Goblin Fire Fiend must be blocked if able.
{R}: Goblin Fire Fiend gets +1/+0 until end of turn.