Great primier! But how about further lowering costs with Birds of Paradise?
Also I disagree with your opinion about Savage Ventmaw because you can use his ability DURING battle like e.g. Scion's ability or Scourge of Valkas buff and rest for enchantments or artifacts
Anyway that's a very good primier to read - I'm trying to build The Ur-Dragon deck myself here: Bow before Draconic King!!!

Vlasiax I can understand why you think Birds is good. But in my experience playing karrthus before this deck and this version now, having little mana dorks that don't scale usually tend to not be worth and hurt you. Because when it eventually comes down to top decking after you've already ramped out, you want to be ripping big dragons off the top of your library instead of a bunch of little mana creatures. The mana creatures I included scale really well at any point in the game and can make a huge impact where as Birds only gets me ahead on one mana. Sure it's great as a turn 1 play but if you're not playing it on turn one, it just feels like a waste. Plus the dragons don't start coming in til about the 4/5 mana range so going from 1 mana to 3 mana turn two doesn't feel worth it for a slot.

And while I do still think Savage Ventmaw is an excellent dragon, in conjunction with Ur-Dragon's ability which is how I want to be cheating stuff into play seems really bad. Using the effect for a 4/4 flyer that won't do anything til the next turn and has potential of dying when they're already wanting to kill your field seems too risky when I'd rather play a dragon with an ETB. I've actually been playing this a quite about without him and haven't really noticed the need for him. As long as I have some type of ramp card in my opening hand, usually come out of the gates pretty well positioned!

That's reasonable, thanks for clarifying that to me, however I can't let go to my little Ventmaw :D
Also have you considered any tutors for this deck? Namely Vampiric Tutor, Demonic Tutor, Enlightened Tutor and Eladamri's Call? I think that it'd boost the consistency of the deck

Vlasiax At some point in the future, I would upgrade Sarkhan's Triumph to Vampiric Tutor and maybe add Eladamri's Call or Demonic Tutor. But other than that, don't really need any other tutors.

I also have another question - what are your thoughts about rest of the fetchland cycle (ZEN Fetches) and Lairs, especially: Darigaaz's Caldera and Rith's Grove?
Another way of very efficient ramp could be Exploration and Crucible of Worlds in case someone blows the table with Armageddon or things like that

Vlasiax If I could include the other fetches I would. However, they're the most expensive ones so adding another $400 for minimal impact on mana base when it's already pretty solid when I could build another deck doesn't seem worth for now. But I would love to at some point in the future.

Played with the Lairs before in other decks. They were too slow and the only tri-lands I really needed were the actual ones. Anymore and you have too many lands entering in tapped.

While I do think utility is important for a deck in terms of land recursion and stuff like that, this deck doesn't have the time to care about it. There is such thing as too much utility. This deck wants to swing out and kill people as quick as possible. So once I get 9 mana for Ur-Dragon, I want to have the resources to amp up the pressure or rebuild instantly if it doesn't work out. And to be honest I don't really care about hitting land drops after I cast Ur-Dragon. That being said, if you spend your early turns setting up for recursion with Crucible and stuff rather than ramping hard or getting the haste and card draw effects out, you lose too much time and resources and sometimes being behind one turn makes or breaks the game with this deck. If you get hit by Armageddon and can't recover from it, oh well it happens. You just know next time to kill them first :)

Have you considered any artifacts that cheat creatures into battlefield like Belbe's Portal, Dragon Arch, Quicksilver Amulet or Kaalia of the Vast?
Also isn't running only 4 basic lands too dangerous?

Vlasiax I have been talking with people on which cheater to include. I think we said that Quicksilver was the best of the 3 to include so that will probably go in the deck at some point. And yes running 4 basics is kinda dangerous for Blood Moon. However, there as been countless times where I fetch almost every turn for dual lands and have still not had enough to cast multiple spells later in the game due to the constrictions on my mana. With this deck, you kinda have to be greedy for the manabase and the next rendition includes less basics. Our deck can function of just using a lot of mountains but if we get Blood Mooned, oh well it happens. It's Commander. Just know to kill them first next time to let them know as long they don't keep tutoring and playing Blon, you won't direct everything at them :)