Mountain

Goblin Mountaineer

Mountainwalk (This creature can't be blocked as long as defending player controls a Mountain.)

Krenko, Mob Boss

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

Mirror Box

The "legend rule" doesn't apply to permanents you control.
Each legendary creature you control gets +1/+1.
Each nontoken creature you control gets +1/+1 for each other creature you control with the same name as that creature.

Krenko's Command

Create two 1/1 red Goblin creature tokens.