Krenko's Command! I'd replace Piker with that. Mogg War Marshal is another better 2 drop.I've never played one of these myself, don't know precisely how good Brightstone will be, but traditionally, emptying your hand in goblins is pretty ridiculous so long as you can find sufficient ways to refill.
I'd cut Goblin Razerunners, Piker, Tunneler, Leyline, all four of your non-goblin creatures, and I'm not entirely sold on a number of the instants and sorceries. Burn isn't typically very good removal in EDH, and there's much better ways to multiply your damage quotient, likeCoat of Arms, Eldrazi Monument,Marton Stromgald, Rage Reflection, Gratuitous Violence, [card]Breath of Fury[/card:
32p9k9wc], etc.
[card]Krenko's Command[/card], Goblin Chirurgeon, Thousand Year Elixir,Battle Hymn, Sparksmith, and Beetleback Chief all seem to be things that other Krenko decks are using, too.
Obsidian Battle-Axe Gives Krenko and other Various Goblins Haste too. Door of Destinies is a slower Coat of Arms that's I find still useful.
Banefire is a great X-Burn card. Goblin Assault and more so Goblin Warrens seem fun.
Goblin Warrens with Krenko and Brightstone seem just fun. [card]Goblin Grenade[
/card] seems like a shoe in as a finisher. Quest for the Goblin Lord is a One Drop that I'd replace one of the slower enchantments with. As a Bonus it works with Krenko.
Mogg Infestation lets you double your creatures or get rid of something game-ending your opponent has.Warbreak Trumpeter might be worth looking into.
Voracious Dragon is a good ender too that took me forever to remember what set it was and that it was more then Dragon-Blah, Blah Goblins.
Mob Justice is a 2nd Goblin War Strike that you pay One more mana for Flavor with.