Trample

Goblin Rock Sled doesn't untap during your untap step if it attacked during your last turn.

Goblin Rock Sled can't attack unless defending player controls a Mountain.

First strike; banding (Any creatures with banding, and up to one without, can attack in a band. Bands are blocked as a group. If any creatures with banding you control are blocking or being blocked by a creature, you divide that creature's combat damage, not its controller, among any of the creatures it's being blocked by or is blocking.)