Deck flavour: Wrath of the Dragon Avatar

A multiplayer voltron control commander deck with reanimator package built for 75% commander meta. The strategy is to ramp as quickly as possible and keep the board clean using mass removal until 7 mana, cast and protect Scion of the Ur-Dragon by searching for a hexproof dragon if required. Next turn transform to deal lethal commander damage to a high threat player (classical combo involves Moltensteel Dragon). Evasion is unnecessary if the board is clean. If unsuccessful, use graveyard recursion and win through Patriarch's Bidding or Living Death paired with Scourge of Valkas or Dragon Tempest. When in doubt, call Nicol Bolas and make oponnent's abandon all hope as their hands are discarded.

Recently cut cards are listed in the sideboard. Currently on the chopping block listed below if any.

Planned upgrades are listed in the sideboard. These are mainly cards I do not yet own but consider playing. Extra notes below if relevant.

Key combos include:
- Scion of the Ur-Dragon + Moltensteel Dragon + Dragon Tyrant
- Scion of the Ur-Dragon + Moltensteel Dragon + Atarka, World Render
- Scion of the Ur-Dragon + Nicol Bolas
- Scion of the Ur-Dragon + Hellkite Tyrant
- Scion of the Ur-Dragon + Silumgar, the Drifting Death
- Scion of the Ur-Dragon + Yosei, The Morning Star
- Scion of the Ur-Dragon + Dragonlord Dromoka
- Worldgorger Dragon + Animate Dead: Infinite enter the battlefield triggers, infinite mana
- Scourge of Valkas + Patriarch's Bidding/Living Death/Twilight's Call

Cards that have been intentionally avoided:

+ Blade of Selves: Only works with non-legendary creatures like Utvara Hellkite, Steel Hellkite or Balefire Dragon. Possibly good with Scourge of Valkas.
+ Bower Passage, Cover of Darkness: We run 10 wrath effects instead and never cast Scion until we have 7 mana.
+ Crucible of Worlds: While excellent with fetch lands, it is usually less practical than Life from the Loam unless one runs cards like Exploration, Azusa, Lost but Seeking and Oracle of Mul Daya. Possibly good in the Hermit Druid/Survival of the Fittest build.
+ Dragonspeaker Shaman, Dragonlord's Servant, Urza's Incubator: If you hardcast dragons, you are playing this deck incorrectly.
+ Feldon of the Third Path: I only want to play dragons in this deck, might make it's way into a more competitive version.
+ Hellkite Charger: Too expensive to work even with Savage Ventmaw.
+ Hermit Druid: Used in fully competitive Scion combo builds, not interested.
+ Mirari's Wake: Doubling lands at 5 CMC is too late, also this deck uses artifact ramp package.
+ Nicol Bolas, Planeswalker: Too high CMC for what he does when he hits the board.
+ Sarkhan's Triumph: You want to fetch dragons to the graveyard, hence you want Entomb instead.
+ Savage Ventmaw: Only makes sense in conjuction with Aggravated Assault.
+ Scourge of the Throne: Generally not reliable and if it does work it's a win-more card.
+ Shields of Velis Vel: Hilarious with Karrthus, Tyrant of Jund but likely not worth it in this deck just for that.
+ Skithiryx, the Blight Dragon: Generally works through Scion's ability and only in conjuction with Moltensteel Dragon, see below. Double strike is not enough and there is no trample. Yes he has regenerate and possible haste, but infect would require a dedicated strategy to be effective (Tainted Strike, Triumph of the Hordes, Grafted Exoskeleton).
+ Survival of the Fittest: Requires a more creature heavy build of the deck where one can use discarding dragons to retrieve essential or high threat pieces.
+ Xenagos, God of Revels: His ability requires you to commit to a choice of a particular dragon before the attack step or he'll just give Scion +4/+4, so it may be better to run Might of the Nephilim or Conqueror's Flail. The haste effect is excellent though.

For references see:

+ Scion of the Ur-Dragon Primer: http://www.mtgsalvation.com/forums/the-game/commander-edh/multiplayer-commander-decklists/217210-scion-of-the-ur-dragon
+ Tolarian Community College - Guide To Scion of the Ur-Dragon EDH: https://www.youtube.com/watch?v=rF_qmKcw-LY
+ Tolarian Community College - How To Build a 5 Color EDH: https://www.youtube.com/watch?v=UleH4wxzONA
+ 5 Color Dragons by Craig Blanchette: http://tappedout.net/mtg-decks/02-06-16-5-color-dragons
+ Who shall I be when I devour your soul?: https://tappedout.net/mtg-decks/who-shall-i-be-when-i-devour-your-soul-1/
+ Scion of the Ur-Dragon EDH (MP, Competitive): http://tappedout.net/mtg-decks/10-03-15-OPi-scion-of-the-ur-dragon-edh-mp-competitive/
+ MagicalHacker - Scion of the Ur-Dragon: http://tappedout.net/mtg-decks/magicalhacker-scion-of-the-ur-dragon/
+ Scion of the Ur-Dragon - JLK by Josh Lee Kwai: http://tappedout.net/mtg-decks/scion-of-the-ur-dragon-jlk/
+ Scion: http://tappedout.net/mtg-decks/25-09-16-scion/
+ EDHREC - Scion of the Ur Dragon - (10.0%) Budget: Expensive: https://edhrec.com/commanders/scion-of-the-ur-dragon-expensive-budget
+ Commander archetypes: http://eternalmagic.com.br/en/2017/06/introduction-on-commander-archetypes/

Any suggestions welcome. Love to hear about any other interesting combos worth including in the deck!