The Legend of the Ur Dragon

Whenever a permanent enters the battlefield tapped and under your control, untap it.

Arcane Sanctum enters the battlefield tapped.

{T}: Add {W}, {U}, or {B}.

{T}, Pay 1 life, Sacrifice Arid Mesa: Search your library for a Mountain or Plains card, put it onto the battlefield, then shuffle.

Flying, trample

Whenever a Dragon you control attacks, it gains double strike until end of turn.

{1}, {T}: Add {W}{U}.

Flying

When Bladewing the Risen enters the battlefield, you may return target Dragon permanent card from your graveyard to the battlefield.

{B}{R}: Dragon creatures get +1/+1 until end of turn.

({T}: Add {B} or {R}.)

As Blood Crypt enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

{T}, Pay 1 life, Sacrifice Bloodstained Mire: Search your library for a Swamp or Mountain card, put it onto the battlefield, then shuffle.

{1}, {T}: Add {R}{W}.

({T}: Add {G} or {U}.)

As Breeding Pool enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Lands you control have "{T}: Add one mana of any color."

{T}: Add one mana of any color.

Flash

This spell can't be countered.

Flying

Discard a card: Until end of turn, Chromium, the Mutable becomes a Human with base power and toughness 1/1, loses all abilities, and gains hexproof. It can't be blocked this turn.

Flying

Whenever Crosis, the Purger deals combat damage to a player, you may pay {2}{B}. If you do, choose a color, then that player reveals their hand and discards all cards of that color.

{T}: Add {C}.

{1}, {T}: Put a storage counter on Crucible of the Spirit Dragon.

{T}, Remove X storage counters from Crucible of the Spirit Dragon: Add X mana in any combination of colors. Spend this mana only to cast Dragon spells or activate abilities of Dragons.

Crumbling Necropolis enters the battlefield tapped.

{T}: Add {U}, {B}, or {R}.

Flying, trample, haste

If Darigaaz Reincarnated would die, instead exile it with three egg counters on it.

At the beginning of your upkeep, if Darigaaz is exiled with an egg counter on it, remove an egg counter from it. Then if Darigaaz has no egg counters on it, return it to the battlefield.

Flying

Whenever Darigaaz, the Igniter deals combat damage to a player, you may pay {2}{R}. If you do, choose a color, then that player reveals their hand and Darigaaz deals damage to the player equal to the number of cards of that color revealed this way.

{1}, {T}: Add {U}{B}.

As Door of Destinies enters the battlefield, choose a creature type.

Whenever you cast a spell of the chosen type, put a charge counter on Door of Destinies.

Creatures you control of the chosen type get +1/+1 for each charge counter on Door of Destinies.

Whenever a creature with flying enters the battlefield under your control, it gains haste until end of turn.

Whenever a Dragon enters the battlefield under your control, it deals X damage to any target, where X is the number of Dragons you control.

Flying, trample

When Dragonlord Atarka enters the battlefield, it deals 5 damage divided as you choose among any number of target creatures and/or planeswalkers your opponents control.

This spell can't be countered.

Flying, lifelink

Your opponents can't cast spells during your turn.

Flying, haste

Other creatures you control have haste.

Whenever an opponent casts a creature or planeswalker spell with the same name as a card in their graveyard, that player loses 10 life.

Flying

Dragonlord Ojutai has hexproof as long as it's untapped.

Whenever Dragonlord Ojutai deals combat damage to a player, look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order.

Flying, deathtouch

When Dragonlord Silumgar enters the battlefield, gain control of target creature or planeswalker for as long as you control Dragonlord Silumgar.

Flying

Whenever Drakuseth, Maw of Flames attacks, it deals 4 damage to any target and 3 damage to each of up to two other targets.

Flying

Whenever Dromar, the Banisher deals combat damage to a player, you may pay {2}{U}. If you do, choose a color, then return all creatures of that color to their owners' hands.

Flying

Whenever a Dragon you control attacks, bolster 2. (Choose a creature with the least toughness among creatures you control and put two +1/+1 counters on it.)

Frontier Bivouac enters the battlefield tapped.

{T}: Add {G}, {U}, or {R}.

({T}: Add {W} or {B}.)

As Godless Shrine enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

{1}, {T}: Add {B}{G}.

{1}, {T}: Add {R}{G}.

({T}: Add {W} or {U}.)

As Hallowed Fountain enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Flying

Whenever Intet, the Dreamer deals combat damage to a player, you may pay {2}{U}. If you do, exile the top card of your library face down. You may look at that card for as long as it remains exiled. You may play that card without paying its mana cost for as long as Intet remains on the battlefield.

({T}: Add {W} or {U}.)

Irrigated Farmland enters the battlefield tapped.

Cycling {2} ({2}, Discard this card: Draw a card.)

{1}, {T}: Add {U}{R}.

Flying

When Jugan, the Rising Star dies, you may distribute five +1/+1 counters among any number of target creatures.

Jungle Shrine enters the battlefield tapped.

{T}: Add {R}, {G}, or {W}.

Flying, haste

When Karrthus, Tyrant of Jund enters the battlefield, gain control of all Dragons, then untap all Dragons.

Other Dragon creatures you control have haste.

Flying

When Keiga, the Tide Star dies, gain control of target creature.

Partner with Sylvia Brightspear (When this creature enters the battlefield, target player may put Sylvia into their hand from their library, then shuffle.)

Flying, haste

Knights your team controls have flying and haste.

Flying

When Kokusho, the Evening Star dies, each opponent loses 5 life. You gain life equal to the life lost this way.

Flying

Whenever a Dragon you control attacks, creatures you control get +1/+0 until end of turn.

Dash {3}{B}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Flying

Whenever another nontoken Dragon enters the battlefield under your control, create a 5/5 red Dragon creature token with flying.

{1}{R}: Dragons you control get +1/+0 until end of turn.

Flying

When Malfegor enters the battlefield, discard your hand. Each opponent sacrifices a creature for each card discarded this way.

({T}: Add {R}.)

Mystic Monastery enters the battlefield tapped.

{T}: Add {U}, {R}, or {W}.

Flying

At the beginning of your upkeep, sacrifice Nicol Bolas unless you pay {U}{B}{R}.

Whenever Nicol Bolas deals damage to an opponent, that player discards their hand.

Flying

When Nicol Bolas, the Ravager enters the battlefield, each opponent discards a card.

{4}{U}{B}{R}: Exile Nicol Bolas, the Ravager, then return him to the battlefield transformed under his owner's control. Activate only as a sorcery.

Flying

When Niv-Mizzet Reborn enters the battlefield, reveal the top ten cards of your library. For each color pair, choose a card that's exactly those colors from among them. Put the chosen cards into your hand and the rest on the bottom of your library in a random order.

Flying

Whenever Niv-Mizzet, Dracogenius deals damage to a player, you may draw a card.

{U}{R}: Niv-Mizzet, Dracogenius deals 1 damage to any target.

This spell can't be countered.

Flying

Whenever you draw a card, Niv-Mizzet, Parun deals 1 damage to any target.

Whenever a player casts an instant or sorcery spell, you draw a card.

Flying

Whenever you draw a card, Niv-Mizzet, the Firemind deals 1 damage to any target.

{T}: Draw a card.

Nomad Outpost enters the battlefield tapped.

{T}: Add {R}, {W}, or {B}.

Flying

Whenever Numot, the Devastator deals combat damage to a player, you may pay {2}{R}. If you do, destroy up to two target lands.

Flying, trample

Whenever O-Kagachi, Vengeful Kami deals combat damage to a player, if that player attacked you during their last turn, exile target nonland permanent that player controls.

Flying, vigilance

Whenever a Dragon you control attacks, tap target nonland permanent an opponent controls. That permanent doesn't untap during its controller's next untap step.

Opulent Palace enters the battlefield tapped.

{T}: Add {B}, {G}, or {U}.

Flying

Whenever Oros, the Avenger deals combat damage to a player, you may pay {2}{W}. If you do, Oros deals 3 damage to each nonwhite creature.

{1}, {T}: Add {W}{B}.

({T}: Add {B} or {G}.)

As Overgrown Tomb enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Flying, vigilance, trample

Palladia-Mors, the Ruiner has hexproof if it hasn't dealt damage yet.

Path of Ancestry enters the battlefield tapped.

{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

When Plaza of Harmony enters the battlefield, if you control two or more Gates, you gain 3 life.

{T}: Add {C}.

{T}: Add one mana of any type that a Gate you control could produce.

When you cast this spell, create X 0/1 red Kobold creature tokens named Kobolds of Kher Keep, where X is the amount of mana spent to cast it.

Flying

Sacrifice another creature: Prossh, Skyraider of Kher gets +1/+0 until end of turn.

{1}, {T}: Add {B}{R}.

Flying

Whenever you cast a spell, put a +1/+1 counter on Ramos, Dragon Engine for each of that spell's colors.

Remove five +1/+1 counters from Ramos: Add {W}{W}{U}{U}{B}{B}{R}{R}{G}{G}. Activate only once each turn.

As an additional cost to cast this spell, sacrifice an artifact.

Search your library for an artifact card with mana value X or less, put it onto the battlefield, then shuffle.

Flying

Whenever Rith, the Awakener deals combat damage to a player, you may pay {2}{G}. If you do, choose a color, then create a 1/1 green Saproling creature token for each permanent of that color.

Flying, haste

Flying

When Ryusei, the Falling Star dies, it deals 5 damage to each creature without flying.

({T}: Add {R} or {W}.)

As Sacred Foundry enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Sandsteppe Citadel enters the battlefield tapped.

{T}: Add {W}, {B}, or {G}.

[+2]: Sarkhan, Dragonsoul deals 1 damage to each opponent and each creature your opponents control.

[−3]: Sarkhan, Dragonsoul deals 4 damage to target player or planeswalker.

[−9]: Search your library for any number of Dragon creature cards, put them onto the battlefield, then shuffle.

Savage Lands enters the battlefield tapped.

{T}: Add {B}, {R}, or {G}.

{T}, Pay 1 life, Sacrifice Scalding Tarn: Search your library for an Island or Mountain card, put it onto the battlefield, then shuffle.

Flying

{2}: Search your library for a Dragon permanent card and put it into your graveyard. If you do, Scion of the Ur-Dragon becomes a copy of that card until end of turn. Then shuffle.

Flying

Whenever Scourge of Valkas or another Dragon enters the battlefield under your control, it deals X damage to any target, where X is the number of Dragons you control.

{R}: Scourge of Valkas gets +1/+0 until end of turn.

Seaside Citadel enters the battlefield tapped.

{T}: Add {G}, {W}, or {U}.

{1}, {T}: Add {G}{W}.

Flying, hexproof

Whenever a Dragon you control attacks, creatures defending player controls get -1/-1 until end of turn.

{1}, {T}: Add {G}{U}.

Flying

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)

{B}: Skithiryx, the Blight Dragon gains haste until end of turn.

{B}{B}: Regenerate Skithiryx.

{T}: Add {C}{C}.

({T}: Add {U} or {R}.)

As Steam Vents enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

({T}: Add {R} or {G}.)

As Stomping Ground enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

({T}: Add {B}.)

Partner with Khorvath Brightflame (When this creature enters the battlefield, target player may put Khorvath into their hand from their library, then shuffle.)

Double strike

Dragons your team controls have double strike.

({T}: Add {G} or {W}.)

As Temple Garden enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Flying

Whenever Teneb, the Harvester deals combat damage to a player, you may pay {2}{B}. If you do, put target creature card from a graveyard onto the battlefield under your control.

Eminence — As long as The Ur-Dragon is in the command zone or on the battlefield, other Dragon spells you cast cost {1} less to cast.

Flying

Whenever one or more Dragons you control attack, draw that many cards, then you may put a permanent card from your hand onto the battlefield.

Flying

Whenever Treva, the Renewer deals combat damage to a player, you may pay {2}{W}. If you do, choose a color, then you gain 1 life for each permanent of that color.

Flying

Whenever Vaevictis Asmadi, the Dire attacks, for each player, choose target permanent that player controls. Those players sacrifice those permanents. Each player who sacrificed a permanent this way reveals the top card of their library, then puts it onto the battlefield if it's a permanent card.

Kicker {3} (You may pay an additional {3} as you cast this spell.)

Flying

When Verix Bladewing enters the battlefield, if it was kicked, create Karox Bladewing, a legendary 4/4 red Dragon creature token with flying.

Flying

Whenever Vorosh, the Hunter deals combat damage to a player, you may pay {2}{G}. If you do, put six +1/+1 counters on Vorosh.

Flying, trample

Whenever Wasitora, Nekoru Queen deals combat damage to a player, that player sacrifices a creature. If the player can't, you create a 3/3 black, red, and green Cat Dragon creature token with flying.

({T}: Add {U} or {B}.)

As Watery Grave enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

{T}, Pay 1 life, Sacrifice Wooded Foothills: Search your library for a Mountain or Forest card, put it onto the battlefield, then shuffle.

Worn Powerstone enters the battlefield tapped.

{T}: Add {C}{C}.

Flying

When Yosei, the Morning Star dies, target player skips their next untap step. Tap up to five target permanents that player controls.