I would say Goblin Warchief in place of Goblin King is a reasonable switch. Also, take Vexing Shusher out of main, and then put some copies in the side, maybe 2 or 3.

Interesting build. I happen to think that Goblins are pretty good as an aggro deck in modern, as they've gotten some recent cards like Collected Company and Atarka's Command to really push the limits of what they can do.

My list is here: This. This is my life now.. It's a tad top-heavy, but otherwise I think it's in a decent place. The main thing that you're really missing imo is a set of AEther Vial. It does innumerable things for dedicated aggro decks that use their curve effectively.

rorofat has a really good goblin primer, ⚠ The ULTIMATE Modern Goblins Primer ⚠, if you want to look at it.

@JDMCRIB Goblin Warchief Is not modern legal, despite the new-framed reprintings.

Looking at this, you're in general going to have a lot of trouble because if you play Eidolon of the Great Revel, you're just going to hurt yourself. A lot.

So first, it's not worth mainboarding, especially since you're not running a lot of burn. Reason being is all of your goblins run 3 CMC or less. Every time you play a spell, you literally kill yourself more. Especially when opponents run protection from red spells, or creatures that gain them one life when a spell is cast. And a lot of decks use it just for the mono red goblin reason. Definitely something to sideboard, and not mainboard.

Second - you do not need 4 of Goblin King. Run one mainboard, one or two sideboard. Yeah, a lot of modern decks run lands with the type mountain in it, however, there are a lot that don't. And even if, Goblin King isn't a win con. It's a situational card. So again, one main board, one or two sideboard.

As well, looking at your mainboard, you have way too many goblin creatures. Yeah, this is tribal, but there are some goblin interactive spells that will seriously help you out a lot in dealing a crap ton of damage early. 35 creatures is seriously overkill. You need some other spell types in your deck.

Foundry Street Denizen pretty much sucks unless you run tokens. Think about it. You're not supposed to be getting past t4 or t5 with goblins, and you'll cast one, maybe two goblins a turn. Four of these is a waste. Having it in the deck is a waste. Definitely something you're gonna wanna get rid of.

Goblin Rabblemaster is something I always disliked as well. It's a weak version of Goblin Piledriver that is extremely slow because it gives you a 1/1 token on your upkeep. As well, it's really dangerous because all your goblins attack each turn if able. You're really susceptible to getting into some sticky situations with that card. Especially in Modern format. They should probably go too. It's a wonderful standard card, and that's about it.

I really don't get why you're running two Cavern of Souls in the sideboard either. Never run land in the sideboard that could easily be used in maindeck. Take out 2 Mountain and put them in!! It's not gonna hurt!! :) And take that Spellskite out of your sideboard too! Yeah, you have a 1 in 60 chance to draw it, but IF you manage to draw it during one of your games, it could give you some really big saves and allow you to win games.

So, for mainboard what I'm recommending is -3 Eidolon, -4 Foundry Street, -4 Goblin Rabblemaster, -1 Goblin King.

With those 12 spaces freed up, I would put in +2 Warren Instigator and fill the playset, +4 Goblin Grenade (because they can win you some games), +1 Spellskite, and maybe if you're crazy enough +4 Hordeling Outburst because it's a pretty useful extra potential 12 goblins for Goblin Piledriver. Then maybe +1 Pithing Needle mainboard for combo decks or what you want.

These are just my recommendations based off of how I play Goblins. However, having some spells other than creatures really does help a little bit when it comes to playing competitively because it gives a lot more substance for your deck, and gives you more options to win.

Maybe if you want, take a look at my goblin tribal and tell me what you think of how it plays! Btw my comments are just recommendations. People have told me in the past that my comments sounds like I'm being an ass to their deck, but I'm seriously not. Thanks for reading and considering them :)

Here's my build: Krenko's Army of Grunts - let me know what you think!

Why not splash green for Atarka's Command over Skullcrack? You can side it out for Blood Moon. Your sideboard looks good, just adjust as needed for the meta. Also Goblin Grenade for reach?

After seeing the comment on people bringing in pro-red creatures, I can see the justification in Skullcrack.

I am contemplating reintroducing Goblin Grenade at least in the side, maybe instead of the 2 mainboard Skullcracks.