Modern Goblins

1 CMC:
4 Foundry Street Denizen
4 Legion Loyalist
4 Signal Pest
4 Goblin Guide

2 CMC:
4 Goblin Bushwhacker (Pseudo-2, at least)
4 Mogg War Marshal
4 Krenko's Command
4 Dragon Fodder

3 CMC:
4 Goblin Chieftain
4 Shared Animosity

Land:
20 Mountain

Sideboard:
1 Forked Bolt
2 Tormod's Crypt
3 Combust
1 Arc Trail
2 Smash to Smithereens
1 Dismember
1 Relic of Progenitus
4 Goblin Assault

 Been playing this a bunch on MTGO and it's so fun and explosive. Quite a few changes since I last played the deck on Cockatrice and Signal Pest has been an all-star. Only issue I have with this deck is that the games are too short.

Goblin Grenade is quite a useful tech at 4, and is better if you're using Goblin Arsonist. It is sorcery speed, but it is definitely one of the better cards in an explosive deck for its cost.

I tested Goblin Grenade (And Lightning Bolt) in this deck before I got it on MTGO, and they're so bloody underwhelming.

The power this deck has is from having as many Goblins as possible and not having cards that don't generate more board presence. I've also never needed the 5 damage as reach and Goblin Arsonist just looks bad compared to other 1 drops I'm not even playing currently.

No VIal?

Vial doesn't really do anything here. It's not like Legacy where I'd have Wastelands and Rishadan Ports to spend my mana on, and it ticks up far too slowly in this deck. It's also not enough like Merfolk where they have a bunch of 2 mana lords to cheat into play mid-combat.