I had forgotten how fun a good combo can be until I played the Paradox deck. I wanted to see if I could find anything workable in Ravnica that could fill that combo void. Of course we still have Nexus/Telfari, but I wanted something new.

I think Experimental Frenzy and Runaway Steam-Kin have promise. With Frenzy, you can cast cards until you run out of mana or hit a land. With Steam-Kin you get 3 mana for every 3 red spells you cast. Each card is playable on it's own, although Frenzy is a bit more limited in use. I am thinking there s an Izzet deck with lots of cheap burn/creatures may be workable. At this point, it is just an idea, but if I get something workable, I will post it after testing. My guess is that it will not be a game winning combo, but will give you card advantage.

With that said, any other combos in the set that you have spotted?

If you are depending on red spells for the Steam Kin don't you think a mono R shell the best instead of Izzet?
....unless you can find a beneficial card for your combo in U that is. If not I'm sure you want to draw a red spell every time. Be nice if you could burn them out of 20 in one turn. It's possible with some Lightnings.

Most the Izzet Spells would have red in them, like Goblin Electromancer and League Guildmage. I really haven't tried to pit it together yet, but I was figuring I would use a few U spells deck manipulation, but depends how it runs. May just go Agro and have the combo as an added bonus.....which would play well to Boros as well.

At this point, just an idea. I just think that they two cards work well together, and they are passable on their own. Most likely will crash and burn, but want to give it a try.

This is what I came up with for Boros. Not great, but a start.

Deck List
Creature(22):
4 x Ghitu Lavarunner
4 x Goblin Banneret
4 x Runaway Steam-Kin
4 x Viashino Pyromancer
4 x Boros Challenger
1 x Tajic, Legion's Edge
1 x Aurelia, Exemplar of Justice
Instant(12):
4 x Shock
4 x Lightning Strike
4 x Wizard's Lightning
Sorcery(1):
1 x Banefire
Enchantment(3):
3 x Experimental Frenzy
Lands(22):
5 x Plains
9 x Mountain
4 x Clifftop Retreat
4 x Sacred Foundry

I watched cgb use frenzy on stream yesterday and just fail due to land clumps.
I'm thinking the solution could be dark dweller Oracle (exiles the top card and let's you play the next one). It would need expendable creatures, but it can potentially keep the cards rolling if you hit too many lands.

The land clumps were/are my concern. That is why I was thinking U initially for some deck manipulation, but it doesn't seem like there is enough good manipulation without using some bad cards.

Still, I will try in Boros and see how it works. More as a card draw mechanic than combo deck. This may be a combo that will work in a few sets, but I think we are missing pieces now.