I like your UG list the best, but you can make some small changes to improve on it still.
What to do:
1. Frost burn weird doesn't belong in the deck if you're not doing devotion. Cut them, gyre sage and the raptors for some sylvan cyratids or voyaging satyr's at the least.
2. A few counters would help the deck a lot. A couple essence scatter and syncopates instead of disperse.
3. Bow of nylea is really good in a deck like this. I'd put in a couple of those.
4. Go up a land if you're worried about the land count, guessing you don't have 4 breeding pools? Temple of Mystery?
5. +2 cyclonic rift.
6. +1 chimera, -1 prophet.
7. +3 divination
Why:
1. You're already clogging the ground with wall of frost, and the ramp and extra mana will help you cast things like primespeaker and hold up counters. The ramp, and extra mana you can get from plasm capture will help with pulkranos (spelling?)
2. 99.99999% of people are going to try and kill you with a creature. Escence scatter is easy to cast and is pure value against most decks. Syncopate is most likey just as useful as escence scatter and can catch other things like planes walkers, which you don't have a real good way to deal without side of just beating them down.
3. Have you every played trading post? Bow of Nylea is like a green better trading post. It makes all your attacks deadly for your opponent, gains life, places counters... it's juicey juicey goodness for a deck like this.
4. yeah so, lands help a lot... no real explanation needed.
5. So gods are hard to deal with, except they are permanents and you can kind of tempo them, with cyclonic rift. And over loaded rift against a mono blue devotion board would be devastating for them.
6. the life gain you get from the chimera is pretty good, and necessary, The prophet inst a win condition and it doesn't really advance your life total or your board. It's good, but not that good, and 2 of the creatures that matter already have flash... the big benefit here is flashing in a prime speaker, which is just kinda "cute", but not really back breaking.
7. you're in blue, you need to utilize it. If not divination then something like inspiration. You need to be able to draw additional cards and 2 prime speakers won't cut it.