I REALLY like this. It reminds me a bit of what I think Alex Sittner's Temur deck at the most recent GP would look like.

I'd consider trying to get the following cards into at least the maybe board for testing.

Hour of Need

Hornet Queen

I'd also consider trying to get 4 Stubborn Denial into the main.

Thanks! I ran Hornet Queen in the Simic deck I ended up turning this into, but I ended up running out of space. Might pull Xenagos, God of Revels for her, since I'm not sure he adds too much. Hour of Need is definitely worth considering too.

I'm not so sure on mainboarding Stubborn Denial , though, especially not four. I guess that really depends on the meta at my LGS.

chord of calling into Hornet Nest is pretty awesome. I have it as a one of with another in the sideboard. I also run 1 Ashcloud Phoenix because it is pretty awesome especially with all the mana you will have! I run 3x Genesis Hydra instead of two, it's just way too good! Let me know what you think :)

I'm trying to figure if I should pull Xenagos, God of Revels for a Hornet Queen in the main, or shuffle around the sideboard and make space for her there. I'm not so sure about Ashcloud Phoenix though. Is there anything in particular you think I should replace with it?

As for Genesis Hydra , I'm pretty happy running two along with the two Chord of Calling . Between those and two Temur Ascendancy along with Courser of Kruphix filtering lands I think I'm in a pretty good place as far as draw power.

No Rattleclaw Mystic? You're the first Temur deck I've seen without it.

I'm personally not a huge fan and much prefer Sylvan Caryatid. The morph honestly doesn't seem like it'd help that much, and Sylvan is much less vulnerable as a hexproof 0/3. I'd rather have my ramp stick around, and it can stall out early-game attackers too.

Ashcloud Phoenix has just been awesome mainly with Prophet of Kruphix out. Its basically invincible except to exile! I haven't played with the temur ascendancy yet, but it seems good, that's what I would probbaly cut. I also run 1 surrak and 1 Arbor Colossus instead of two surraks, just seems more useful.

Rattleclaw Mystic is amazing for ramp and also awesome to dump into a Genesis Hydra! Im running 4 Sylvan Caryatid and 3 Rattleclaw Mystics

Im still not sold on Rattleclaw Mystic. Especially considering the amount of ramp I already have. Ashcloud Phoenix seems like it definitely could have a place though.

Arbor Colossus could have a place at the very least in the sideboard. Although Polukranos, World Eater can hit fliers too with his monstrous.

Polukranos don't kill Stormbreaths.

Its a good deck. Gave the +1. I have a temur deck I've had a lot of success with play testing and playing in tournaments. I've been mashing on people with it and you might get some ideas from it. Check it out. The "Real Deal" Holyfield!(temur).