Atarka, World Render doesn't quite seem to do anything, if you're attacking with a dragon, you don't need it to have double-strike, unless it kills your opponent outright, and if it does, you're likely winning that game even if your dragon doesn't have double-strike.

If I were in your spot, I would want to play 4 Haven of the Spirit Dragon, and maybe 24-25 lands total, since it makes your mana more consistently able to cast dragons, and the haven gets the dragons back in the late game.

Have you considered Avaricious Dragon? the discard clause actually isn't that much of a cost for drawing an extra card every turn, especially when you can start emptying your hand anyway and if you play more Haven of the Spirit Dragon, any dragons you discard can be rebought later.

Also, Sarkhan's Triumph doesn't seem to me like it does much, more dragons might just be better, since, what would you rather cast: Sarkhan's Triumph and Dragonlord Ojutai or Thunderbreak Regent and, say Avaricious Dragon?

For your sideboard: I'm not convinced that Atarka's Command does anything in any matchup, and if you want to have a good plan against control, you need some slots for it. I'd suggest creatures with haste, Gaea's Revenge is the obvious one, Kolaghan, the Storm's Fury is on theme, even if it's off colour, though the colour is slightly offset by Shaman of Forgotten Ways and Haven of the Spirit Dragon, Shaman of the Great Hunt is a nice beater that can make your mana dorks relevant too and Surrak, the Hunt Caller can give a non-hasty dragon haste if he is on the board. And last - Silumgar's Scorn might not be the counterspell you're looking for, especially since your commitment to blue is fairly ligth, Disdainful Stroke might be better.

Whats Abvan Did you mean Abzan?

Yes I meant abzan and thank you for pointing the mistake out