Really good deck! Original idea love it a lot, +1 from me.

Feel free to checkout my deck and let me know what you think Competitive Goblins

You might consider looking into trample effects. You could even run a Bosh, Iron Golem to bash and sac your Wurmcoil Engine s for more value.

@Fizzery: thanks, your deck is really cool too! Jund Hackblade might be my favorite card, I have a cheap rakdos aggro deck that I use for fun (not on here, though I should put it up).

@enpc: thanks for the advice, i'll test him out. My one concern is that the only artifact that I will be able to sac effectively is Wurmcoil Engine , but with welder out, that shouldn't be a problem

Splash blue for Dack Fayden and add Liquimetal Coating . Dack helps throw things in the grave and combos with the coating to steal your opponent's biggest threat for good. It also gives you acess to another artifact land.

Mimic Vat could also be a great card because your welder can fetch it in response to a kill spell, target himself with it, and then get a haste welder every turn to keep your shenanigans up.

Well, the problem I see with Mimic Vat is that it costs 3 mana to use, and despite all the ramp, this deck can't produce 3 mana very reliably each turn, as the ramp is usually all used up in one or two burst on turn one or two to rip through the deck. Also, Liquimetal Coating is super cool, but it doesn't do quite enough for the deck. It does have some cool synergies with goblin welder, but it is not good enough to take up a deck slot. It would probably just end up as fodder for the welder to sacrifice for 2 mana, which doesn't make much sense since I have a bunch of 0 mana artifacts to sac. Dack Fayden is interesting, I'll try it out, but my gut feeling is that he will be a little slow. He might do something for the long game, but my hand should be pretty much empty after turn 2. We'll see. Thanks for advice!

Also, usually Wurmcoil Engine is bigger than my opponent's threat, or at least can kill their biggest threat.

None of those suggestions (with the exception of adding Seat of the Synod that was implied in my blue splash) was intended as mainboard options. I was playing against your deck with some heavy control decks, specifically W/B and junk decks and realized that you had a bit of a weakness to them that your current "screw blue" sideboard doesn't answer so I thought of some options that would be good against them.

Also Shrapnel Blast could be useful. Sac a relic for the wurm, swing with the wurm, sac the wurm for a blast and then the babies for the mom.

Oh OK, that makes more sense, thanks for clarifying. I think if I do put in the blue splash, I'll probably revert to Intuition as my method of choice for getting the wurms in the yard (search for 2 wurms and a land or something, so they have to put in at least 1 wurm). One of the reasons I moved away from the blue was to make the deck a little more wallet friendly, as removing the fetchlands and Intuition shaved off like $400, but I'll test it out again

Love the Welder! This was my version that I played a while ago Onulet's Go Infinite, might give you some ideas. +1 for the Welder!

Btw, I still think you need to mainboard at least a pair of Sundering Titan s, on turns 2-3, especially with the prevalence of 3-4 color decks in the format, you can literally blow up your opponent's entire mana base by putting him into play, attacking the next turn, and then triggering his ability again by sacrificing him for either another copy of himself (which would make me laugh) or another wurm.

Also, sideboard either Meekstone or Ensnaring Bridge to defend against Eldrazi or any creature-based glass-cannon build.