Hi all,
Wanted to share my latest list I've had a lot of success and fun with (34-8 on Champion ladder: ~80% winrate). I'm a big fan of Rainbow decks and after Blue-Purple decided to experiment with some other combination and style. This is a much more late-game bomb deck (as opposed to the more aggressive BP rainbow), using the game-turning purple and orange bombs. Overall, it just has a lot of options, which makes for very interesting games.
As with any midrange rainbow deck, I value the 3-drop slot heavily (because of the coin) as they are the key to control the early board and this colour combination has some great 3-drops in the Ifreet, Engine and Barkeep. Besides the sheer power of the late game bombs, a major asset of the decks success is the utility of the enchantments. Knowing which enchantments to keep in which match-up is quite important (instead of auto-burning enchantments).
Particularly the Cliffs have been very instrumental in many matches, shutting down racers, trapezists and ringmaster clears (against ice wall for instance). Also the ping can be surprisingly useful as removal as I don't run racers. Overall I don't like low-value cards in Rainbow. I honestly think midrange rainbow decks don't need many 1/2 drops and the 3+ drop curve is much more important. With Red Cliffs and Sword Saint it's easy to stabilize against aggro. The two Eager Recruits I often end up burning, but can be useful to activate the Cliffs, put on Treasury of Petra for draw, or just chump block. It's also nice to have a target to retrieve from the boneyard with a 3-drop on Five Spirit Gate.
The card I'm most on the fence about is Celestial Dragon (the curve into Armageddon Angel is nice, but often I don't like the risk of the giving the immortal ring). I'm also often considering a second pocket instance as I love the battle trick, but this suite of enchantments has been very rewarding up to now. Maybe a Five Spirit Gate can be dropped for it (early versions were like that).
In terms of Budget variant, this deck would really lose some power and utility, but can still be decent. Doing more of a desert theme in Orange (with Mardykhors and Wurms) and using some other purple biggies (Colossus) is certainly possible (replacing Daigoju, Dragon, Jin-Sook, Kushiel, Gale). Armageddon Angel and Perfect Grade are super strong though, but they should be the first mythics to craft from these respective colours. Not having To Heaven and Back does mean a large loss in value, but that is not necessary every game anyway. When doing budget replacement make sure to have some decent 4-drops, as curving out is more important with less swing cards. I particularly like Aimless Vessel as beefy 4-drop.