Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Rootbound Crag

Rootbound Crag enters tapped unless you control a Mountain or a Forest.
{T}: Add {R} or {G}.

Goblin Rally

Create four 1/1 red Goblin creature tokens.

Mountain

Hordeling Outburst

Create three 1/1 red Goblin creature tokens.

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.

Ogre Battledriver

Whenever another creature you control enters, that creature gets +2/+0 and gains haste until end of turn. (It can attack and {T} this turn.)

Goblin Trashmaster

Other Goblins you control get +1/+1.
Sacrifice a Goblin: Destroy target artifact.

Burn Bright

Creatures you control get +2/+0 until end of turn.

Krenko, Mob Boss

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

Krenko's Command

Create two 1/1 red Goblin creature tokens.

Krenko, Tin Street Kingpin

Whenever Krenko, Tin Street Kingpin attacks, put a +1/+1 counter on it, then create a number of 1/1 red Goblin creature tokens equal to Krenko's power.

Obelisk of Urd

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
As Obelisk of Urd enters, choose a creature type.
Creatures you control of the chosen type get +2/+2.

Copperline Gorge

Copperline Gorge enters tapped unless you control two or fewer other lands.
{T}: Add {R} or {G}.

Goblin Instigator

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

Parallel Lives

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Chatterfang, Squirrel General

Forestwalk (This creature can't be blocked as long as defending player controls a Forest.)
If one or more tokens would be created under your control, those tokens plus that many 1/1 green Squirrel creature tokens are created instead.
{B}, Sacrifice X Squirrels: Target creature gets +X/-X until end of turn.

Hobgoblin Bandit Lord

Other Goblins you control get +1/+1.
{R}, {T}: Hobgoblin Bandit Lord deals damage equal to the number of Goblins that entered the battlefield under your control this turn to any target.

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.