Dragon Breath

Enchant creature
Enchanted creature has haste.
{R}: Enchanted creature gets +1/+0 until end of turn.
When a creature with mana value 6 or greater enters, you may return this card from your graveyard to the battlefield attached to that creature.

Carnelian Orb of Dragonkind

{T}: Add {R}. If that mana is spent on a Dragon creature spell, it gains haste until end of turn.

Archwing Dragon

Flying, haste
At the beginning of the end step, return this creature to its owner's hand.

Earthquake Dragon

This spell costs {X} less to cast, where X is the total mana value of Dragons you control.
Flying, trample
{2}{G}, Sacrifice a land: Return this card from your graveyard to your hand.

Atarka Monument

{T}: Add {R} or {G}.
{4}{R}{G}: This artifact becomes a 4/4 red and green Dragon artifact creature with flying until end of turn.

Dragonlord's Servant

Dragon spells you cast cost {1} less to cast.

Miirym, Sentinel Wyrm

Flying, ward {2}
Whenever another nontoken Dragon you control enters, create a token that's a copy of it, except the token isn't legendary.

Sarkhan, Dragonsoul

+2: Sarkhan deals 1 damage to each opponent and each creature your opponents control.
−3: Sarkhan 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.

Mountain

Ambitious Dragonborn

This creature enters with X +1/+1 counters on it, where X is the greatest power among creatures you control and creature cards in your graveyard.

Nogi, Draco-Zealot

Dragon spells you cast cost {1} less to cast.
Whenever Nogi attacks, if you control three or more Dragons, until end of turn, Nogi becomes a Dragon with base power and toughness 5/5 and gains flying.

Breath Weapon

Breath Weapon deals 2 damage to each non-Dragon creature.

Draconic Muralists

When this creature dies, you may search your library for a Dragon card, reveal it, put it into your hand, then shuffle.

Crucible of the Spirit Dragon

{T}: Add {C}.
{1}, {T}: Put a storage counter on this land.
{T}, Remove X storage counters from this land: Add X mana in any combination of colors. Spend this mana only to cast Dragon spells or activate abilities of Dragons.

Thrakkus the Butcher

Trample
Whenever Thrakkus attacks, double the power of each Dragon you control until end of turn.

Korlessa, Scale Singer

You may look at the top card of your library any time.
You may cast Dragon spells from the top of your library.

Ganax, Astral Hunter

Flying
Whenever Ganax or another Dragon you control enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Choose a Background (You can have a Background as a second commander.)

Island

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.

Verix Bladewing

Kicker {3} (You may pay an additional {3} as you cast this spell.)
Flying
When Verix enters, if it was kicked, create Karox Bladewing, a legendary 4/4 red Dragon creature token with flying.

Crucible of Fire

Atarka, World Render

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

Lathliss, Dragon Queen

Flying
Whenever another nontoken Dragon you control enters, create a 5/5 red Dragon creature token with flying.
{1}{R}: Dragons you control get +1/+0 until end of turn.

Acolyte of Bahamut

Commander creatures you own have "The first Dragon spell you cast each turn costs {2} less to cast."

Demanding Dragon

Flying
When this creature enters, it deals 5 damage to target opponent unless that player sacrifices a creature of their choice.

Chaos Dragon

Flying, haste
This creature attacks each combat if able.
At the beginning of combat on your turn, each player rolls a d20. If one or more opponents had the highest result, this creature can't attack those players or planeswalkers they control this combat.

Sarkhan the Masterless

Whenever a creature attacks you or a planeswalker you control, each Dragon you control deals 1 damage to that creature.
+1: Until end of turn, each planeswalker you control becomes a 4/4 red Dragon creature and gains flying.
−3: Create a 4/4 red Dragon creature token with flying.

Dragon's Hoard

Whenever a Dragon you control enters, put a gold counter on this artifact.
{T}, Remove a gold counter from this artifact: Draw a card.
{T}: Add one mana of any color.

Astral Dragon

Flying
Project Image — When this creature enters, create two tokens that are copies of target noncreature permanent, except they're 3/3 Dragon creatures in addition to their other types, and they have flying.

Forest

Dragon Broodmother

Flying
At the beginning of each upkeep, create a 1/1 red and green Dragon creature token with flying and devour 2. (As the token enters, you may sacrifice any number of creatures. It enters with twice that many +1/+1 counters on it.)