You could probably replace Dragon Tempest with Rhythm of the Wild , if you're really looking for the redundancy with that effect, unless you really like Dragon Tempest 's effect, and if you find that it really pays off for you. You could probably switch any of your land tutor spells for Growth Spiral , if you really feel you need that card in there. You probably don't need it, though. A card like that, you'll likely hold until you have a land in your hand. A card like Rampant Growth , however, you won't likely hold. Something to consider.

A card you might consider for this deck, and one I find usually pays dividends in Big Dumb Animal decks like this, is Sunbird's Invocation . Cast a dragon with this in play, and you'll likely end up playing another dragon for free.

Hope this helps.

I don't think Rhythm is worth a spot in here, seems like a redundancy that's not needed due to your commander.

As for growth spiral, I would look at maybe Roar of the Crowd or Cancel . Roar seems like it has a high CMC for what it does, especially when you're likely to chose dragons. Since they have such a high CMC you're unlikely to have enough out to make it worth running over another stronger burn card, such as Comet Storm or such.

As far as other adjustments, I would try and make the following swaps:

Cancel for Voidslime

Hedron Archive for Worn Powerstone

Spell Rupture for Negate (most things you want to counter will be noncreature spells)

Mana-Charged Dragon for Stormbreath Dragon

+1 from me, I like dragon decks.