Why did you go for Haven of the Spirit Dragon which can be used only once, only for your commander and costs 3 lands to tap , when you could use Volrath's Stronghold which can cycle all your creatures, indefinitely, and costs 3 lands to tap? :)
You know Prossh can kill with one hit if the opponent is tapped out and you still have your 6 Kobolds with the following cards
Berserk (trample) 22/5 Prossh
Psychotic Fury 11/5 double strike Prossh
Temur Battle Rage (trample) (double strike) 11/5
Armed/Dangerous (lure on attacking kobold, sac at blocker's step) 11/5 double strike Prossh
Tainted Strike - 12/5 infect Prossh
Your creatures are giving too much advantage to enemies who run Bribery, aka every blue deck. The creatures you put in shouldnt be useful to a blue opponent in blocking or killing your creatures at all.
Food Chain is the most important enchantment for this deck. It's "I win" if you have a haste effect or Blood Artist. At Instant speed even.
You should use effects that bring Xenagos or Craterhoof in for a one shot kill even if your Prossh is killed the turn you played it. Pattern of Rebirth is one. Natural Order is another. Defense of the Heart can also be considered. Chord of Calling taps the kobolds which will be sacrificed to Prossh. Green Sun's Zenith is just ok for Xenagos.
Prossh can easily be countered, killed at sorcery speed, or killed in response to saccing kobolds.
What you aim should be "Yeah but you cant counter these 6-8-10.. Kobolds". There are great cards for 5 mana that draw a card for each creature you control. Devour, or as sorcery. Cards like Coat of Arms, Beastmaster's Ascension, Garruk Wildspeaker, Craterhoof Behemoth, Vicious Shadows, Sacrifice Outlets, Gaea's Cradle..
Sarkhan Vol both makes your Prossh and your Kobolds hasty with +1/+1 and steals blockers to sacrifice to Prossh. Wont even tell you how awesome it is to drop Sarkhan after a Doubling Season. 10x 4/4 Dragons is lethal if you have haste effect. Still something that requires an immediate answer while you play your Prossh next turn with haste.
You can sell the Toxic Deluge for a lot of dollars and get.. Crux of Fate. Sacrifice Kobolds to Prossh. Crux of Fate non-dragons and attack :)
Cream of the Crop doesn't work with Kobolds because they have 0 power..
Shizo, Death's Storage is great when they have flying blockers for your Prossh. It's not even a tap land.
You have an unprotected attacking 5 toughness creature. He is easily killed by any deck once you cast him on turn 6. Instead get a lot of mana elves, and ramp and put him out on turn 3. Kill on turn 3 or 4.