Goblins!

Things I'd consider:

Chaos Warp: Otherwise you'll be in trouble when someone slaps a Pariah on a Heliod or drops a Grave Pact with a token/sac engine or Propaganda next to a Ghostly Prison. I'd probably slot it in over Fury Charm.

Illusionists's Bracers: Double the tokens Krenko craps out. You're running Rings, but they stack and it doubles your chances of drawing one.

Chaosphere : Not sure where I'd slot it in but it makes fliers a lot easier to deal with.

Gratuitous Violence: Over Dictate of the Twin Gods or Furnace of Rath. it's a tough call. Yeah, you can flash in Dictate, and I would imagine you plan is to do so when you can deliver the killing blow so the fact that it helps everyone won't matter, but the reality is there are a lot of situations where it's going to be a card you really don't want on the board. Plus there will be times where you play it, think you're going for the killing blow, and someone instants a Fated Ret or Rout or just plain old fogs, and you've got to deal with double damage coming at you the next turn. On the other hand Dictate and Furnace both do effect non-combat damage like Vicious Shadows or Purphoros. I'm not sure there's a wrong answer to be honest. Maybe just run all three as GV stacks with the others :)

Viashino Heretic: Over Torch Fiend. Yeah, it's one more to cast and one more to activate, but it's reuseable and it deals damage equal to the artifact's cost.

Glacial Crevasses: It can buy you a whole lot of turns of taking zero damage.

Vandalblast: I'd probably run it over Smelt. You still have one instant-speed artifact removal, and this costs the same as Smelt to hit one thing at sorcery speed, but it has the option to overload and destroy everyone's artifacts but yours.