A multicolor-tribal control deck with a dragon subtheme
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WU 5, WB 4, WR 4, WG 7, UB 5, UR 5, UG 7, BR 6, BG 7, RG 5
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Consider (have):
37th land
* Nine-Fingers Keene - 4/4 menace for 4 who (usually) ramps on combat damage, and has a good chance of drawing a bunch of cards later in the game
** UB: Baleful Strix - Good blocker that cantrips
** WU: Soulherder - Flickering Niv every turn to draw a bunch more cards, Bladewing to reanimate more dragons, Silumgar/Evil Twin to change what I get, or just "untap" a dragon that attacked
* UB: Hostage Taker - Removal and (probably) ramp in one
WB Primevals' Glorious Rebirth - Get a very scary board quickly, but requires at least one legend first
* UR: Prismari Command - Flexibility
RB: Kardor, Doomscourge - This will often kill some things, while also probably dealing some damage. At the very least it gives me a turn off
BG: Casualties of War - Remove a bunch of stuff
BR: Rivaz of the Claw - Dragon synergy
WB: Mortify - Cheap, flexible removal
WB: Fracture - Cheap removal, but can't hit creatures
RB: Corpse Explosion - Cheap sweeper, but requires a fatty in the yard
UR: Galvanic Iteration - Copy any instant or sorcery, with flashback
UR: Sprite Dragon - Cheap dragon that can grow over time
Borderposts - Ramp that Niv can hit, but slow
Commander's Sphere - Ramp of any color, but on a colorless card
BR: Hurl Through Hell - Removal that can get me a threat
WU: Brago, King Eternal - Blink Niv
WU: Mistmeadow Witch - Blink Niv for card draw, or save something from a sweeper
BG: Binding the Old Gods - Removal and ramp
WU: Turn to Mist - Cheap way to blink something (Niv) or save something from removal, even a sweeper
* WB: Kaya's Guile - Except for clearing graveyards, these effects are pretty minor, and the card is not going to be relevant in all games
BG: Putrefy - Hard removal with some options
UW: Teferi, Time Raveler
UG: Rashmi - Could possibly draw some cards or let me get in a few more spells every turn cycle
UB: The Scarab God - A resilient win condition
UG: Simic Charm - Protect my stuff from targeted removal, win a combat or bounce a thing
WG: Sylvan Reclamation - Gets two things and makes them gone for good, or can get a land in an emergency
UB: Lim-Dûl's Vault - Kind of a tutor if I need a specific type of answer
BR: Grave Upheaval - Reanimate from anyone's yard and even give it haste, but it's really expensive. Can cycle for a basic land if we need some fixing or are struggling to find lands
RG: Reap the Past - Get back a bunch of stuff
RG: Domri, Anarch of Bolas - Better used in a creature-focused deck
WR: Aurelia, the Warleader - What's scarier than a few dragons hitting you? When they hit you twice every turn!
UG: Tatyova, Benthic Druid - Sure, it's nice to draw a card and gain a life every land drop, but without a lot of ways to get extra lands on the field, this is probably going to be quite underwhelming as a 5-drop
RG: Mina and Denn, Wildborn - I don't think I will have lots of extra lands to play, and although using the extra drop for the activated ability to give a dragon trample is nice, it's not going to be relevant all that often and a lot of my lands will etb tapped
WR: Gisela, Blade of Goldnight - Win every combat and kill really quickly
UB: Thief of Sanity - Very Dimir card. Evasive beater that steals their cards (and mills a little). Much less impressive in EDH than 60-card 1v1, though
WU: Linvala, Shield of Sea Gate - Protect my board against a sweeper
UG: Kruphix, God of Horizons - I don't have a lot of ways to generate large amounts of mana, nor do I have a lot of ways to spend large amounts of colorless mana consistently, but it's a decent way to store mana for later
UB: Atris, Oracle of Half-Truths - Card draw on a stick
BR: Garna, the Bloodflame - Great as a response to a sweeper, but I need to keep up 5 mana just in case of a sweeper, which is not ideal if I don't have something else to spend it on. I also still have to recast the creatures. Leaving behind a haste-giver is nice though
UG: Kiora, Behemoth Beckoner - Draw cards when dropping dragons while ramping, giving pseudo-vigilance or untapping the Door
WU: Azorius Charm - Lifelink is sweet with big dragons, but we probably have better ways to solve the problems this solves
WG: Selesnya Charm - Removal, get a blocker or trample through a big dude
UB: Dimir Charm - Counter a sweeper or kill a utility creature
RG: Treacherous Terrain - Finisher or get a missing land
WB: Profane Procession // Tomb of the Dusk Rose - Removal into threats
WR: Response // Resurgence - Extra combat, or removal
BR: Angrath's Rampage - Edict with some flexibility
RG: Savage Twister
UB: Discovery // Dispersal - Cheap card selection that can put some stuff in the yard to bring back, or a tempo play to slow my opponents down and possibly even deal with a big threat
BG: Infuse with Vitality
WB: Ethereal Absolution
* WR: Gerrard, Weatherlight Hero - Sweeper protection
* UR: Niv-Mizzet, Dracogenius - Dragon, card draw and even removal
UR: Goblin Electromancer - Not sure how often I will be able to use the reduction of generic mana
UR: Invert // Invent - Trick or tutor
Thought Vessel - Early ramp that lets me keep the good stuff
Dragon Tempest - Hasty dragons with some extra value
UB: Connive // Concoct - Reanimation
UB: Extract from Darkness - Reanimation
BG: Gloomshrieker - A body that gets back a card
WB: Debtors' Knell - A way to get back Niv when he's too expensive to put in the zone, and other creatures if I'm missing a wincon, but it's probably too expensive
UR: Marchesa's Smuggler - Haste-giver
UG: Gretchen Titchwillow
WG: Fracturing Gust
UG; Eureka Moment - A smaller, instant speed Urban Evolution
UG: Double Major - Get an extra Niv, or just some other big guy
Rienne, Angel of Rebirth - Pumps all my creatures, but more importantly it brings them back if they get wrathed
WR: Deflecting Palm - Stop a huge burn spell or dude
UG: Repudiate // Replicate - Stifle an ability or copy something, e.g. Niv to draw more cards. Most of our creatures are either legendary or a dork, though, and we have enough Simic
BG: Garruk, Apex Predator
BG: Gaze of Granite
UG: Progenitor Mimic
UG: Altered Ego
UG: Nissa, Steward of Elements
UR: Expansion // Explosion
UW: Azor, the Lawbringer
UW: Cloudblazer

Miirym - Get copies of my dragons
Bound // Determined - Sac Niv to get back 5 cards, or make sure an important spell resolves
Cascading Cataracts - Fixing
Scion of the Ur-Dragon - Tutor up whichever dragon I need for the turn, and then maybe even get it back with one or my getter-backers
Qasali Pridemage - Artifact/enchantment removal that turns Niv into a 3-turn clock
Samut, Tyrant Smasher - Haste
Claim // Fame - Can give me a hasty dude, but first I need to get it to the graveyard, probably by reanimating a mana dork
Cut // Ribbons - Removal and wincon
Fist of Suns, Jodah
Grand Arbiter Augustin
Beckon Apparition - Cheap, instant speed graveyard hate
Assure // Assemble - Protect a good thing like Ramos or make some dudes
Cauldron Haze - Boardwipe protection
Unmake - The mana cost is somewhat prohibitive, but it's an efficient removal spell that deals with the problem for good
Shielding Plax - Protection, mostly for Ramos
Aurelia's Fury - Silence all relevant opponents before going off with Ramos
Heartwarming Redemption - Redraw my hand
Lightning Helix
Ride Down - Remove a blocker and sneak in some damage
Shattering Blow - Get rid of an artifact for good
Tajic, Legion's Edge - Protect my dudes from red sweepers
Double Negative - Izzet hard counter with possible upside
Dramatic Rescue - Save a creature from removal
Mogis, God of Slaughter - Bleed my opponents dry of resources
Master of Cruelties - Punish people for having their blockers killed
Malfegor - Rakdos dragon that can trade cards in hand for a Plague Wind effect
Swift Warkite - Rakdos dragon that can bring back a cheap value dude
Harbinger of the Hunt - Gruul dragon that can repeatedly sweep small things, but costs quite a bit to use
Niv-Mizzet, the Firemind - I don't have a lot of extra draw, but this guy does fuel himself, and the Dracogenius also helps
Azorius Guildmage - Very Azorius. Keep things tapped or stop unsanctioned abilities. Quite the mana sink, though.
Obzedat's Aid - Bring back any permanent
Golgari Findbroker, Acolyte of Affliction - Golgari ways to get back cards into hand, but only get permanents
Prime Speaker Zegana - Can get huge and draw a full new hand, but if it does, it probably means I have a dragon or two already. Consider if I am lacking in big card draw
Dovin's Acuity - Draw a card, gain a little life, and re-use this later
High Priest of Penance - Cheap and great rattlesnake
Kunoros - Stop graveyard shenanigans
Sin Collector - Hand control and early board presence
Wrecking Ball - Removal with the option of killing a land, but a bit on the expensive side
Allure of the Unknown - Big draw, but I risk my opponent getting a dragon
Void
Toil // Trouble - Card draw or burn
Pilfered Plans - Draw a few cards and mill a little
Sundering Growth - Enchantment/artifact removal that can gain extra value if we have tokens
Possessed Skaab - Get something back from the yard
Izzet Chronarch - Get back a spell
Soul Manipulation - Counterspell and/or get back a dragon from the yard
Turn // Burn
Torrent of Souls - Although getting back a hasty fatty from the yard is nice, this isn't really amazing before we're in Christmas land

Consider (dont have):
* Navigation Orb - Cultivate for gates, you just have to spend an extra 2 before you can actually use it
Basilisk Gate - Make Niv able to two-shot (or even one-shot) someone
$$ RG: Klauth, Unrivaled Ancient - A mostly better Ventmaw
WG: Jenson Carthalion - Scry on multicolour cast, and filter mana to ensure all 5 colors
UB: Ertai Ressurected - Counterspell or removal
UR: Wandering Mind - Card selection on a flier
Esika, God of the Tree // Prismatic Bridge - Since I don't have a lot of other creatures, this should get me a dragon on upkeep most turns
WG: Knight of New Alara - Gives +2/+2 to all my dudes, and makes Niv a two turn clock
Quandrix Command - Counterspell with some extra utility options
RG: Black Market Tycoon - Mana dork
$$ Klothys, God of Destiny - Ramp
$$ Inkshield - Fog that gets me a big board
$ Reinterpret - Counter that lets me still play other spells
$ Samut, Voice of Dissent - Give my dragons haste
$ Scion of Draco - Upgrade all my dudes, but hard to discount with my manabase
Pyrrhic Revival
Back for More

Karrthus, Tyrant of Jund - Haste for all my dragons, and make sure I'm the only one with dragons
Kenrith - Does everything. Most importantly haste+trample, card draw and even reanimation!
Swerve - Counter-esque
Cerebral Vortex - Instant speed Sign in Blood that can kill someone who's drawing a lot
$ Cindervines - Upfront removal that can help me clock players as well
Reconstruct History
Boros Guildmage - Give out haste
Fires of Yavimaya - Hasty dragons
$$ Dragonlord Kolaghan - Hasty dragon that gives my other dudes haste
$ Blot Out the Sky
Intimidation Bolt - Remove something small and stop a huge attack
Draconic Disciple - Ramp in Gruul that also supports the dragon theme
Steward of Valeron, Atzocan Seer - Ramp in Selesnya
Spring // Mind - Land based ramp that can be used as an expensive divination later
Destined // Lead - Protection or a lure
Weaver of Currents - Ramp in Simic, but only for colorless
Sunder Shaman - Repeatable artifact/enchantment removal
Aura Mutation - Enchant removal with a payoff
Thrash // Threat - Removal or just get a medium dude
Sigil of the Nayan Gods
Shield of the Oversoul
Pollenbright Wings
Novablast Wurm
Razia's Purification - Armageddon and sweeper in one, but everyone gets to keep three things
Bright flame - Sweep tokens and gain some life
Vengeful Rebirth - Get back a card and maybe deal some damage, but probably too expensive
Spellbreaker Behemoth - Auto-resolve Niv and other wincons
Nulltread Gargantuan - Reuse Niv
Pale Recluse - Fixing
Omnibian - Elkify a thing for a turn each turn
Atarka's Command - Versatile including ramp, but all effects are relatively minor
Mercy Killing - Removal spell that is more fitting for a group hug deck
Double Cleave - Double strike a big dude
Fight to the Death - Sweep away chump blocked dudes or prevent damage triggers
Moonhold - Get a turn off from someone after a sweeper
Powerstone Minefield - Prevent small attackers
Response // Resurgence - Removal for an attacker or let me shave off a turn for my alpha strike
Waves of Agression - Extra combats when I have extra lands
Sarkhan the Mad - Boom?
Sarkhan Vol
Lore Drakkis
Primal Empathy
$$ Voidslime
$ March of the Multitudes
$$$ Hunting Grounds
Rip Apart

Considerations that are in other decks:
Skull Prophet - Muldrotha, BG ramp
Rootcoil Creeper - Muldrotha, UG ramp
Kaya, Ghost Assassin - Queen Marchesa
Escape to the Wilds - Wort
Arixmethes - Rashmi
Bedevil - Rakdos
Last One Standing - Rakdos
Drown in the Loch - Modern Shadow

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Possible cuts:
* WU Ojutai, Soul of Winter - Tapping things down when my dragons attack is nice, but this is very expensive and I probably won't have THAT many dragons
WU Render Silent
* WR Velomachus - Technically has 24 possible hits, but they are mostly situational, and probably not worth playing a 7 mana 5/5 for
WR Boros Charm
WG Dragonlord Dromoka - Other decks might need this, and besides being a dragon it doesn't really synergize a lot
WG Eladamri's Call - Do I have enough important creatures to tutor for?
WG Mirari's Wake
WG Reborn Hope
WG Dromoka the Eternal
UB Evil Twin
UB Dragonlord Silumgar
UR Hypersonic Dragon
UR Counterflux
UR Izzet Charm
UR Ionize
UG Oko - Can't really protect it
BR Dreadbore - A bit slow?
BR Kolaghan, the Storm's Fury - Hasty and can really pump the team, but doesn't do that much on a clear board
BR Bladewing the Risen - Very expensive for a 4/4, but great value when it's two dragons for the price of one
BR Dreadbore
BR Kolaghan's Command
* BG Deathsprout - 4 mana is quite a bit for removal that can only hit a single creature, even if I get to ramp
BG Treasured Find
BG Golgari Charm

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Considered but cut before first play:
Ashen Rider - Too expensive and not really synergistic
Angel of Despair - A worse Ashen Rider
* Cunning Breezedancer - Potentially a finisher, but unlikely
Drogskol Reaver - Too expensive as a source of cards when I don't have a lot of other life gain
River Hoopoe - Card draw, but fragile and expensive to use
Risen Reef - Seems to be the only elemental, at which point it's probably not worth it
Azra Oddsmaker - Risk a card to draw two, but I'm not sure I'll often be in a position to attack
Jhessian Zombies, Sanctum Plowbeast - A little bit of fixing, but as bodies they are wholly unimpressive
Necrotic Sliver - A Vindicate on a creature, but without other slivers this just doesn't seem worth it in a deck not focused on graveyards or death triggers
Nightveil Specter - A nice way to get some card advantage, but I lose the cards if this dies, which makes it a bit too unreliable for the small body
Kydele, Chosen of Kruphix - This is much better in a dedicated wheel deck
* Consuming Aberration - Can be a strong finisher, but it doesn't have evasion and does require some setup before it gets very threatening, meaning I can't just drop it and go for a kill
* Vampire Charmseeker - Way too expensive if no one helps me cast it, but can be used politically
Get the Point - Too expensive considering it only hits creatures
Haunter of Nightveil - Too expensive for the relatively minor effect
Species Gorger - It's nice to recast Niv every turn, but he does cost 5
Final Payment - Cheap removal, but as a control deck the additional cost could be steep, and there is more flexible removal in the colors
* Justice Strike - Cheap removal, but not very reliable, unlike Orzhov options
* Mindswipe - Izzet counterspell that can also kill people, but I'm unlikely to have lots of mana to dump
Necromancer's Covenant - Expensive to cast, not guaranteed to do anything for me, we have enough Orzhov cards with the removal suite, and I'd rather win with dragons
Ethereal Absolution - Expensive, we have other Orzhov stuff in removal, and this effect is not amazing with a few big dudes as opposed to a bunch of small dudes
Guild Summit - Can draw up to 10 cards per game, but will probably usually not draw more than maybe 3, and is very timing specific if you don't want to pay a lot for those extra cards (when you draw this after the gates). Not worth the mono-color
* Assemble the Legion - Takes a few turns before it's worth it, and I still don't think I'll be winning in this deck with a bunch of 1/1s that don't have any other synergy
Outlaws' Merriment - A much worse Assemble the Legion
* Captive Audience - Very expensive, and allowing our other opponents to get 5 zombies each could be very dangerous
Fractured Identity - I don't really want to give my opponents things
* Basilica Bell-Haunt - Tricky mana cost with a minor effect
Lochmere Serpent - Not amazing when we don't have the lands to sac, and we probably won't with a budget manabase
Magister of Worth - I don't have enough control over what the result will be, and while it'd be nice to reanimate a bunch of dragons, if I spend the entire game killing stuff I probably don't want my opponents to get all their dead stuff back
Keranos, God of Storms - He just isn't that likely to be active and his effect is pretty minor. Probably better used in a chaos deck or one that puts lots of U and R pips on the board
Ravos, Soultender - The anthem effect isn't going to do much, and a raise dead every turn is not what I want to pay 5 for
Baloth Null - Only gets back creatures, and it might be hard to make use of the full 2, in which case I would rather want something cheaper
* Soul Ransom - Will likely either steal something mediocre, or get removed at an inopportune time if it has stolen something important
Ashiok, Nightmare Weaver - Getting something good is probably going to take some turns, and we're probably going to struggle with protecting it
* Ashiok, Dream Render - Graveyard and tutor hate, but I'm not set up for protection planeswalkers and this just doesn't do anything for me if my opponents aren't doing tutoring or shenanigans
Doom Foretold - Probably better in stax deck, an enchantment deck or an aristocrats style deck
Role Reversal - I probably don't have a lot of things I want to trade away, and at that point this just doesn't do enough
* Rakdos, the Showstopper - With no way of manipulating the outcome of the flips, this is very expensive for a partial board wipe. Save for the chaos deck
Deputy of Detention - A second Detention Sphere but on a fragile body. With access to both black and green, I'd rather permanently deal with problems than put them under a fragile body, especially when playing sweepers myself
Mercurial Chemister - In a deck that is not focused on drawing cards specifically, has access to black and white for better removal, and does not do extra untapping, this does not seem like it belongs and deserves a spot at cmc 5
Vivid Revival - More or less a draw 3 except you get to choose which 3, but I don't really want to re-use the same cards again and again, and I have enough other card draw. Usually worse than All Suns' Dawn, and I don't want too many mono-colored cards
Ancient Excavation - Doesn't gain card advantage, and doesn't draw cards when you really need it (no or few cards in hand). I don't need the graveyard synergy, but the land cycling is nice
Dream Trawler - This just isn't an amazing EDH card, and would probably take the slot of a dragon
Detention Sphere - Nice against tokens, but I think I have enough permanent answers to things that I don't need an O-ring when I don't have enchantment synergies
Restoration Gearsmith - Gets back a dragon or a Door, but with the low artifact count, I'd rather play one of the Golgari options that get permanents
* Cauldron Dance - Fun card and really good with Bladewing. Without him we can still flash in some blockers. But it's probably too expensive, and too aggro focused
Silumgar's Command - This can do a lot of things, but it's probably expensive for most combinations of two because each of the modes are somewhat restricted
* Nahiri, the Harbinger - She can be removal or redraw some cards. The dream is to ult her to get Bladewing to get back a dragon I pitched to her plus, then replay him next turn to get back another. Or Ramos then go off. Or just get The Ur-Dragon.
Ajani Vengeant - His plus doesn't do enough and I have to use it too many times to get to the ult. I'm never going to be able to protect him for that long, and even if I do, I'm only ruining one player's day
* Emergency Powers - The thought of using this to restock and drop a dragon for free is nice, but I don't want to fill up my opponents' hands, and I'm not guaranteed to even draw something I can drop
Sorin, Grim Nemesis - Removal or card draw that also works as a clock

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Cuts after playing:
* Ramos - Works great if I can follow it up with Niv, Conflux or the Ur-Dragon, but otherwise it will take 3 more spells before it does anything significant
* The Ur-Dragon - Really expensive to cast and not two-color, but it is a heavy hitter and can help me snow-ball
Down // Dirty - I'm probably never using the Mind Rot side of this, so it's just a slightly overcosted regrowth
Conflux - Expensive but flexible. A two-color tutor would probably be sufficient, though
Villainous Wealth - Not two-color, I don't have tons of extra mana for a big X, and I probably have enough dragons to win
Invoke the Firemind - Not worth it if I can't pump a lot of mana into it
Sphinx's Revelation - Not great if I can't dump a bunch of mana into it, and I'm not exactly lacking in drawing power with Niv
Crucible of the Spirit Dragon - Are storage lands even worth playing? Dragons are expensive and I play a lot of instants, so I should be able to get some use out of this, but the Dragons-only restriction might be a bit rough
Sandsteppe Citadel - Replaced with The World Tree
* WU Dragonlord Ojutai - Cheap for a dragon and draws cards, but I don't have a lot of stuff to keep him safe besides Minamo. With so many ways to bring cards back from the yard, I probably don't need this as the Nth dragon
UG Gyre Engineer - Too slow/fragile?
* WR Leave // Chance - Save some dudes from removal or my own sweeper, or bounce Niv to re-use the trigger. Can later be used to swap out duds in my hand
UG Plasm Capture - Very restrictive cost, and while the mana drained is nice to dump into big dragons, I'm probably not going to be able to cast this a lot of times when I don't have a lot of lands already
Door to Nothingness - Can only be used once, and 15 mana is a lot and it instantly puts a target on me
Minamo - Can untap a lot of things for pseudo-vigilance, but might not be worth it without Ojutai
UR Cloven Casting - Very expensive, and a lot of my spells aren't really worth copying (e.g. sweepers)
WG Nature's Chant - A bit narrow, and I probably have enough of these
RG Zhur-Taa Druid - Too fragile
UG Maraleaf Pixie - Too fragile
WR Solar Blaze - "Full cost" sweeper that doesn't kill everything
WB Utter End - Expensive for spot removal, but it can deal with indestructible threats
UG Urban Evolution - Expensive, but provides both card draw and sustainable ramp, assuming I have a land in hand
? Tome of the Guildpact - Having cards in hand isn't really hard, but this does make sure I never run out, and it's ramp that doesn't die to sweepers. It is quite expensive, though
WU Taigam, Ojutai Master - Makes most my stuff uncounterable, or can let me re-use some spells, but is relatively fragile and might not be able to attack safely
RG Savage Ventmaw - A dragon that ramps when it attacks, but the color combo it creates is not the most useful, and ramping at 6 isn't super useful
BG Find // Finality - Find can only get creatures, and Finality is a very expensive sweeper that might not kill the scariest things
Reliquary Tower - Colorless land, and I have enough recursion and redundancy that I probably don't need the effect
? All Suns' Dawn - Somewhat expensive and requires me to have a yard, but 5-for-1 is pretty good
WU Absorb - Low flexibility, and the 3 life probably doesn't matter that much
? WR Deafening Clarion - Can only sweep somewhat small creatures, but the option of getting lifelink could be useful
WB Kaya's Wrath - Difficult casting cost, and probably don't need this many sweepers
UB Notion Rain - Basically Read the Bones. Good enough?
? UR Expressive Iteration - I often won't be able to play the second spell, which makes this an expensive cantrip
? Haven of the Spirit Dragon - Only really works for the 10ish dragons, but that does include Niv