Given the three copies of Krenko and four of Cleaver Riot, 18 lands feels light. Goblin King is your best bet to add, as that means you won't need to retain Volcanic Strength to get mountainwalk. The Bushwhackers are a good low-end option, and their kicker option is cheap and powerful. The Balloon Brigades and Tunnelers are good targets to drop so you can get to 60, and trimming a couple of Flunkies wouldn't hurt. Also, while the artifacts are nice, both come off as distractions here. The Ring of Valkas doesn't do much more than a kicked Bushwhacker, and the creature gives you a creature and affects all creatures with haste. Meanwhile, the Dragn's Claw could be cut back to two copies and not really cost you anything. Having three cards at the 4-spot and another half dozen at the 5-spot makes this pretty pricey for goblins, which again points to possible ways to cut cards and make the whole thing faster.