Sundial of the Infinite in response to the exile trigger means you get to keep the dragon you tutored.

And that's something that's already listed on his deck. ;)

I dunno if Scrying Sheets is worth having over Cavern of Souls or even just another mountain. As far as I can tell, it only hits one card in your deck, so you're investing 3 mana on a very low chance that you're gonna hit a card. It just seems meh.

All Snow-Covered Mountains are also snow permanents, so if any basic land is on top I can draw it.

Oh, I guess it hits the Mountains too. I didn't realize that, but even then I don't know if it's better than a Cavern. even then there's not too large of a chance you're gonna hit anything.

My group doesn't use very much blue so it's not really an issue right now but I see why making Zirilan of the Claw uncounterable is good. The recent price hike to ~$50 is also a little too much for a land currently (I'm building a couple other decks), but I am planning on buying one eventually. But back to Scrying Sheets, it draws a card about half the time, which I think is pretty good. I've got lots of mana rocks/doublers so the cost isn't much of an issue.

Flameshadow Conjuring and Mimic Vat?

I already run Flameshadow Conjuring, but the Mimic Vat is interesting. I don't run many ways to kill my dragons, though, so I wouldn't always be able to use it.

Haven of the Spirit Dragon, Thunderbreak Regent, Sarkhan's Triumph, Dragon Whisperer, Ruby Medallion, Dragonloft Idol, Dragonlord's Servant are all great in dragon-tribal decks.

I'm actually not planning on casting dragons from my hand (I almost exclusively tutor for them) so the cards that lower their cost are not very effective in this deck. I may try Haven of the Spirit Dragon, though.

I don't know if saccing lands is the way to go with Zirilan though. But that reminded me of Elixir of Immortality for graveyard recursion. Wouldn't that go well here?

It would, but I like the Haven because it takes a land spot. But it also means I have less mountains to double mana/Spawn of Thraxes. I'm still thinking about it.

You said you want to make it faster? Braid of Fire Desperate Ritual

Braid of Fire is an awesome addition to Zirilan. I can attest to that. :)

Do you have problems with it not really helping for three turns? Since you get the mana during your upkeep it can only be used for untapping artifacts and tutoring with Zirilan before the main phase starts, I feel like it might be a bit too slow for me.

I have no problems at all. 2 mana for an Enchantment that pays for itself? What's there not to like? Free artifact and Zirilan actovatios? Sounds quite good. Even better if cast on the 2nd turn.

+1 for the title!

Mordant Dragon for utility on killing problem creatures i.e Prophet of Kruphix, Seedborn Muse, or Oracle of Mul Daya?

It's a little underwhelming, since Balefire Dragon can hit all of their creatures and Spawn of Thraxes and Kilnmouth Dragon can hit it without attacking. Thanks for the suggestion, though.

I'm digging the king crimson reference!

King Crimson!

Dictate of the Twin Gods would be perfect for this. Why is it not a thing?

you have Myriad Landscape twice. XD

+1 for Red.

So, I was going through Battle for Zendikar spoiler list, looking for singles to add to my wishlist and noticed Akoum Hellkite. You're going to add it in, right? It sounds awesome with your Worldgorger Dragon.