Niv-Mizzet, Guildpact

Flying, hexproof from multicolored
Whenever Niv-Mizzet deals combat damage to a player, it deals X damage to any target, target player draws X cards, and you gain X life, where X is the number of different color pairs among permanents you control that are exactly two colors.

Dragon Mage

Flying
Whenever this creature deals combat damage to a player, each player discards their hand, then draws seven cards.

Adult Gold Dragon

Junji, the Midnight Sky

Flying, menace
When Junji dies, choose one —
• Each opponent discards two cards and loses 2 life.
• Put target non-Dragon creature card from a graveyard onto the battlefield under your control. You lose 2 life.

Claim Territory

Search your library for up to two basic Forest cards, reveal them, put one onto the battlefield tapped and the other into your hand, then shuffle. (Also shuffle this card.)

Bloomvine Regent

Flying
Whenever this creature or another Dragon you control enters, you gain 3 life.

Bloomvine Regent // Claim Territory

Knollspine Dragon

Flying
When this creature enters, you may discard your hand and draw cards equal to the damage dealt to target opponent this turn.

Call the Spirit Dragons

Dragons you control have indestructible.
At the beginning of your upkeep, for each color, put a +1/+1 counter on a Dragon you control of that color. If you put +1/+1 counters on five Dragons this way, you win the game.

Exude Toxin

Each non-Dragon creature gets -X/-X until end of turn. (Then shuffle this card into its owner's library.)

Scavenger Regent

Scavenger Regent // Exude Toxin

Dragonologist

When this creature enters, look at the top six cards of your library. You may reveal an instant, sorcery, or Dragon card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
Untapped Dragons you control have hexproof.

Incinerator of the Guilty

Flying, trample
Whenever this creature deals combat damage to a player, you may collect evidence X. When you do, this creature deals X damage to each creature and planeswalker that player controls. (To collect evidence X, exile cards with total mana value X or greater from your graveyard.)

Kilnmouth Dragon

Amplify 3 (As this creature enters, put three +1/+1 counters on it for each Dragon card you reveal in your hand.)
Flying
{T}: This creature deals damage equal to the number of +1/+1 counters on it to any target.

Sunscorch Regent

Flying
Whenever an opponent casts a spell, put a +1/+1 counter on this creature and you gain 1 life.

Shiko, Paragon of the Way

Flying, vigilance
When Shiko enters, exile target nonland card with mana value 3 or less from your graveyard. Copy it, then you may cast the copy without paying its mana cost. (A copy of a permanent spell becomes a token.)

Betor, Kin to All

Flying
At the beginning of your end step, if creatures you control have total toughness 10 or greater, draw a card. Then if creatures you control have total toughness 20 or greater, untap each creature you control. Then if creatures you control have total toughness 40 or greater, each opponent loses half their life, rounded up.

Dragonspeaker Shaman

Dragon spells you cast cost {2} less to cast.

Ancient Bronze Dragon

Flying
Whenever this creature deals combat damage to a player, roll a d20. When you do, put X +1/+1 counters on each of up to two target creatures, where X is the result.

Flameblast Dragon

Flying
Whenever this creature attacks, you may pay {X}{R}. If you do, it deals X damage to any target.

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon enters, choose a creature type.
Spells of the chosen type you cast cost {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay.
Other creatures you control of the chosen type get +1/+1.

Maelstrom of the Spirit Dragon

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a Dragon spell or an Omen spell.
{4}, {T}, Sacrifice this land: Search your library for a Dragon card, reveal it, put it into your hand, then shuffle.

Necromaster Dragon

Flying
Whenever this creature deals combat damage to a player, you may pay {2}. If you do, create a 2/2 black Zombie creature token and each opponent mills two cards.

Diviner of Mist

Flying
Whenever this creature attacks, mill four cards. You may cast an instant or sorcery spell from your graveyard with mana value 4 or less without paying its mana cost. If that spell would be put into your graveyard, exile it instead.

Ancient Hellkite

Flying
{R}: This creature deals 1 damage to target creature defending player controls. Activate only if this creature is attacking.

Goldspan Dragon

Flying, haste
Whenever this creature attacks or becomes the target of a spell, create a Treasure token.
Treasures you control have "{T}, Sacrifice this artifact: Add two mana of any one color."