Livaan, Cultist of Tiamat

Whenever you cast a noncreature spell, target creature gets +X/+0 until end of turn, where X is that spell's mana value.
Choose a Background (You can have a Background as a second commander.)

Lava-Field Overlord

Assist (Another player can pay up to {7} of this spell's cost.)
Flying
When Lava-Field Overlord enters the battlefield, it deals 4 damage to target creature an opponent controls.

Thran Dynamo

Star Compass

Star Compass enters the battlefield tapped.
{T}: Add one mana of any color that a basic land you control could produce.

Fire Diamond

Fire Diamond enters the battlefield tapped.
{T}: Add {R}.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Dragon Mage

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

Fellwar Stone

{T}: Add one mana of any color that a land an opponent controls could produce.

Bogardan Hellkite

Flash
Flying
When Bogardan Hellkite enters the battlefield, it deals 5 damage divided as you choose among any number of targets.

Utvara Hellkite

Flying
Whenever a Dragon you control attacks, create a 6/6 red Dragon creature token with flying.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Dragon's Approach

Dragon's Approach deals 3 damage to each opponent. You may exile Dragon's Approach and four cards named Dragon's Approach from your graveyard. If you do, search your library for a Dragon creature card, put it onto the battlefield, then shuffle.
A deck can have any number of cards named Dragon's Approach.

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Ganax, Astral Hunter

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

Ancient Copper Dragon

Flying
Whenever Ancient Copper Dragon deals combat damage to a player, roll a d20. You create a number of Treasure tokens equal to the result.

Sol Ring

Shockmaw Dragon

Flying
Whenever Shockmaw Dragon deals combat damage to a player, it deals 1 damage to each creature that player controls.

Scourge of Valkas

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.

Terror of the Peaks

Flying
Spells your opponents cast that target Terror of the Peaks cost an additional 3 life to cast.
Whenever another creature enters the battlefield under your control, Terror of the Peaks deals damage equal to that creature's power to any target.

Aurora of Emrakul

Flying, deathtouch
Whenever Aurora of Emrakul attacks, each opponent loses 3 life.

Cryptolith Fragment

Cryptolith Fragment enters the battlefield tapped.
{T}: Add one mana of any color. Each player loses 1 life.
At the beginning of your upkeep, if each player has 10 or less life, transform Cryptolith Fragment.

Cryptolith Fragment // Aurora of Emrakul

Coldsteel Heart

Coldsteel Heart enters the battlefield tapped.
As Coldsteel Heart enters the battlefield, choose a color.
{T}: Add one mana of the chosen color.

Lathliss, Dragon Queen

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.

Prismatic Lens

{T}: Add {C}.
{1}, {T}: Add one mana of any color.

Mountain

Red Dragon

Flying
Fire Breath — When Red Dragon enters the battlefield, it deals 4 damage to each opponent.

Neheb, the Eternal

Afflict 3 (Whenever this creature becomes blocked, defending player loses 3 life.)
At the beginning of your postcombat main phase, add {R} for each 1 life your opponents have lost this turn.

Hellkite Punisher

Flying
{R}: Hellkite Punisher gets +1/+0 until end of turn.

Explosive Crystal

Explosive Crystal deals 4 damage divided as you choose among any number of targets. (Then exile this card. You may cast the creature later from exile.)

Amethyst Dragon

Amethyst Dragon // Explosive Crystal

Thrumming Stone

Spells you cast have ripple 4. (Whenever you cast a spell, you may reveal the top four cards of your library. You may cast spells with the same name as that spell from among the revealed cards without paying their mana costs. Put the rest on the bottom of your library.)

Hoarding Dragon

Flying
When Hoarding Dragon enters the battlefield, you may search your library for an artifact card, exile it, then shuffle.
When Hoarding Dragon dies, you may put the exiled card into its owner's hand.

Rapacious Dragon

Flying
When Rapacious Dragon enters the battlefield, create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")