Dragons Triumph

[Bambi^]

Changed commander to Scion until Hellkite Courser arrives. Need to figure out, which card I discard for him. Gaea's Blessing could be a choice (just got one mill deck in our play round) My thought would be: as long there's no mill: Ur-Dragon commander + Hellkite Courser. If there is any milling: switch Hellkite for Gaea's and take Scion as the commander? Or rather discard a Card to get both of them into my deck?

Revision 59

Added/removed cards:
-1 Sarkhan Unbroken
+1 Gaea's Blessing
+1 Living Death

Changed amounts:
-1 (Main) +1 (SB) Hellkite Courser

[Elan Morin Tedronai]

Why not The Ur-Dragon itself?

[Bambi^]

This was my choice aswell.
If I play with the Ur Dragon as my commander, Scourge of the Throne gets sideboarded.
If Scion is my Commander, Ur Dragon gets Sideboarded and replaced with scourge of the throne.

Which one I play depends on which decks my mates play. Scion is way more consistent but won't do any good if my graveyard gets exiled :/

[drekow]

Just took a quick look, but for your mana curve 25 lands are way too little. I don't know how you planned to play that many high mana cost cards. I tried to look at 10 starting hands with the starting hand feature and looked to turn 3 and only one of the 10 hands was what i would call playable. My guess is that you should have between 36-38 lands depending on how your mana curve looks after cutting cards to a the lands. I would also recommend to try to have more lands that enter untapped and not be reliant on having amulet of vigor to play on curve as only playing tapped lands is like playing one turn behind people that are not.

I also have a The Ur-Dragon dragon tribal deck and it was my first EDH deck built from the Ur-dragon precon deck, so i'm very familiar with 5-color Dragon tribal. if you want to have a look here is the deck list:
  https://deckstats.net/decks/142156/1429930-might-of-the-ur-dragon-s-brood/

I don't know your playstyle or what you want your deck to do, but I kan give some examples of playstyles and how to cheat in your big dragons.
 - If you want to get many big dragons out reanimation is a great way. Note: Scion of the ur-dragon might be a better commander for this. Here
   cards like haunting voyage, living death and patriarch's bidding are great cards. And a dragon like Moonveil Regent can help you put cards in
   graveyard.
 - If you want to cheat in dragons in an other way, than Sneak Attack, Purphoros, Bronze-Blooded, Selvala's Stampede, Lurking Predators and
   Defence of the Heart are great cards. I also like Oath of Druids but its a risky card.
 - Last style I know is better with Morophon, the Boundless and it is trying to get to cast your dragons for free by reducing the casting cost with
   Morophon, the Boundless, herald's horn, Ursa's Incubator and other cost reducers. Or Fist of Suns/Jodah, Archmage Eternal + Morophon, the
   Boundless.

Also you are missing the best card in any EDH deck with The Ur-Dragon as its commander and that is Hellkite Courser. 5 mana for a 6/5 and you get your commander out for free  with haste without increasing the commander tax. This allows you to use The Ur-dragons attack trigger to Draw cards and put down 1 permanent from hand for free.

If you want some help with suggestion on what to cut for more lands than I would need you to try to explain what you want the deck to do and what cards you are not willing to cut.

Hope some of this was helpful and just remember that not all tips are right for all people as playstyle, power level, local meta and what we like and want out of the game are different.

Another creature you can use to bring out the dragons for cheap is Elvish Piper. Dragonspeaker Shaman will reduce the cost of dragon spells by 2 colorless. I am also a fan of Timeless Lotus and Crystal Quarry for my 5 color decks.

[Bambi^]

Already bought some new cards and replaced them with others as you can see. At first I just sideboarded The Ur-Dragon for Scourge of the throne, depending on who's the commander. Now i put Forbidden Orchard into my deck aswell, to get the Oath of druids trigger more easily and consistent. With Scion of the ur dragon as my commander the deck runs pretty smooth by now. I think for The Ur-Dragon as the commander I still have to add more lands, but I can't decide which cards to drop. By now I can react very well to many actions.

Revision 66

Added/removed cards:
+1 Evolving Wilds
+1 Fabled Passage
+1 Forbidden Orchard

Changed amounts:
-1 (Main) +1 (SB) Fellwar Stone
-1 (Main) +1 (SB) Hellkite Courser
-1 (Main) +1 (SB) Vedalken Orrery

[Bambi^]

Removed Combo to bring creatures for free, cuz of lack of usage while playing. Added more ramp to raise consistency

Revision 69

Added/removed cards:
+1 Cultivate
+1 Kodama's Reach
+1 Nature's Lore
+1 Nissa's Pilgrimage
+1 Rampant Growth
+1 Search for Tomorrow
+1 Skyshroud Claim
+1 Three Visits

Changed amounts:
-1 (Main) +1 (SB) Chromatic Orrery
-1 (Main) +1 (SB) Fist of Suns
-1 (Main) +1 (SB) Lathliss, Dragon Queen
-1 (Main) +1 (SB) Morophon, the Boundless
-1 (Main) +1 (SB) Panharmonicon
-1 (Main) +1 (SB) Time Warp
-1 (Main) +1 (SB) Timeless Lotus
-1 (Main) +1 (SB) Urza's Incubator

[Bambi^]

Revision 71

Added/removed cards:
+1 Carnelian Orb of Dragonkind
+1 Cavern-Hoard Dragon
+1 Dream Halls
+1 Exotic Orchard
+1 Invasion of Tarkir // Defiant Thundermaw
+1 Last March of the Ents
+1 Orb of Dragonkind
+1 Pillar of Origins
+1 Rivaz of the Claw
+1 Sarkhan, Soul Aflame
+1 Steely Resolve
+1 Tooth and Nail
+1 Urza's Ruinous Blast

Changed amounts:
-1 (Main) +1 (SB) Atsushi, the Blazing Sky
-1 (Main) +1 (SB) Demonic Tutor
-1 (Main) +1 (SB) Diabolic Tutor
-1 (Main) +1 (SB) Dictate of the Twin Gods
-1 (Main) +1 (SB) Evolving Wilds
-1 (Main) +1 (SB) Fabled Passage
-1 (Main) +1 (SB) Forbidden Orchard
-1 (Main) +1 (SB) Gaea's Blessing
-1 (Main) +1 (SB) Galazeth Prismari
-1 (Main) +1 (SB) Grim Tutor
-1 (Main) +1 (SB) Reliquary Tower
-1 (Main) +1 (SB) Savage Beating
-1 (Main) +1 (SB) Talisman of Progress