This deck has quite a few ways to win, and this deck seems very complicated at first. It is. But here are the win conditions in no particular order.
After getting Scion of the Ur-Dragon out, attack with him so that he is unblocked. Use his ability and search for Skithiryx, the Blight Dragon. In response, use his ability again and search for Moltensteel Dragon. Then after that resolves, in response to the other ability, activate his Moltensteel Dragon ability 6 times, paying 12 life. Then once everything resolves, you will have attacked with a 10/4 infect creature. Game over.
Total cost: WUBRG, 12 life.
If you have Tandem Lookout, Curiosity,
Snake Umbra
, Ophidian Eye, Mind Over Matter, Keen Sense, or
Helm of the Ghastlord
in your hand during the course of the game, play that card enchanting/soulbounding Scion of the Ur-Dragon. Then at the most opportune time, pay 2 mana, searching for Niv-Mizzet, the Firemind. Tap to draw a card. Drawing a card will deal a point of damage. Dealing that damage to a player will draw you a card, or you can discard it with Mind Over Matter to untap Niv-Mizzet, the Firemind and tap him to draw you a card. That can be repeated for each card in your deck, but it might not be enough, so play
Tireless Tribe
when you have a chance and discarding Ulamog, the Infinite Gyre or Kozilek, Butcher of Truth when you can. That will let you go infinite. Game over.
Total cost: Having and playing one of the seven cards mentioned above, WUBRG.
If you have Fireshrieker, Grafted Exoskeleton, Grappling Hook, Inquisitor's Flail,
Double Cleave
, Psychotic Fury, Tainted Strike, Armed / Dangerous, Assault Strobe, Ajani, Caller of the Pride, True Conviction, Runes of the Deus, Rage Reflection, Gratuitous Violence,
Glistening Oil
, Furnace of Rath, Corrupted Conscience, Battle Mastery, Silverblade Paladin, or Gisela, Blade of Goldnight, and you have an opponent who cannot block flying, and you have another card with a CMC of 8 or more, play the card in your hand equipping/enchanting/soulbounding Scion of the Ur-Dragon. Then, pay two and search for
Spellbound Dragon
, attack that player, discard the card of CMC 8 or more, and swing for either 21 commander damage in one turn or 10 infect in one turn. Game over.
Total cost: Having and playing one of the 20 cards mentioned, having one of 9 cards in the deck with a CMC of 8 or more, WUBRG.
If your opponent has lots of artifacts, you can first attack with Hellkite Tyrant then next turn attack with a beefed up
Hellkite Igniter
for 2 mana if you have 10 artifacts, 4 mana if you have 5 artifacts, or 6 mana if you have 3 artifacts. Game over.
Total cost: Your opponent and you having a total of 10 artifacts and WUBRG or your opponent and you having a total of 5 artifacts and 1WUBRG.
If there's someone at the table everyone else wants dead (and it's surprisingly not the person with this deck), Scion of the Ur-Dragon can search for Mana-Charged Dragon for lethal Commander damage.
Total cost: A unanimously agreed scarier enemy, WUBRG.
If you have Grafted Exoskeleton, Corrupted Conscience, Tainted Strike, Inquisitor's Flail, Furnace of Rath, Gratuitous Violence,
Glistening Oil
, or Phyresis in your hand, play them on Scion of the Ur-Dragon at the most opportune time. Then pay 2 to search for Dragon Tyrant and attack for lethal commander damage or infect damage. Game over.
Total cost: Having and playing one of the 8 cards mentioned, WUBRG.
If you have Patriarch's Bidding in your hand, use Scion of the Ur-Dragon to pitch Karrthus, Tyrant of Jund, Thundermaw Hellkite, and any number of other creatures to the graveyard, then cast Patriarch's Bidding for a nasty load of creatures to attack with. Game over.
Total cost: Having and playing Patriarch's Bidding, WUBRG.
If you have Necromancy in your hand, you can use Scion's ability to pitch Worldgorger Dragon to the graveyard. Then go ahead and Necromancy it back out. Doing so will flicker your entire field infinite amount of times. Using this technique, tap all your lands in response each time to create infinite amounts of each color. Once this occurs, in response to the next Worldgorger Dragon trigger, pay two to pitch Niv-Mizzet, Dracogenius to the graveyard, and use your infinite amount of red and blue to deal infinite damage to everyone. While this is happening, if someone gets a response, you can draw your whole deck, play
Tireless Tribe
and discard Ulamog, the Infinite Gyre or Kozilek, Butcher of Truth with a whole bunch of cards to keep yourself safe. (Patriarch's Bidding is a card you can use in the hand to bring back a buttload of dragons.
Total cost: Having Necromancy in your hand and WUBRG.
After the first win condtion, if another player is open, search first for Teneb, the Harvester, deal damage, and reanimate Skithiryx, the Blight Dragon. Next turn, search for
Moonveil Dragon
and pump him up 6 times. Game over.
Total cost: WUBRG and 2RRRRRR.
Other than that, there are other neat things you can do:
You can protect Scion of the Ur-Dragon from being killed/exiled/stolen/shuffled into your library by searching for Chameleon Colossus,
Clockwork Dragon
, Keiga, the Tide Star, Kokusho, the Evening Star,
Quicksilver Dragon
, Ryusei, the Falling Star, or
Zodiac Dragon
.
You can destroy fields by first searching for Ryusei, the Falling Star (if your opponent is about to kill Scion of the Ur-Dragon),
Scourge of Kher Ridges
, or Balefire Dragon and responding to your own ability by searching for Moonglove Changeling, giving deathtouch, then resolving abilities.
You can rid players of answers by searching for Nicol Bolas or Dragon Mage right before dealing damage.
WHEW! Longest description I've ever done. Now I got a headache. Thanks, Scion of the Ur-Dragon.
