An Offer You Can't Refuse

Counter target noncreature spell. Its controller creates two Treasure tokens. (They're artifacts with "{T}, Sacrifice this token: Add one mana of any color.")

Fearsome Awakening

Return target creature card from your graveyard to the battlefield. If it's a Dragon, put two +1/+1 counters on it.

Bad River

Bad River enters tapped.
{T}, Sacrifice Bad River: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

Preordain

Scry 2, then draw a card. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Flux Channeler

Whenever you cast a noncreature spell, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Pseudodragon Familiar

Flying
{2}{U}: Target creature gains flying until end of turn.

Command Tower

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

Nimbleclaw Adept

Bigby's Hand — {T}: Untap two other target permanents. Activate only as a sorcery and only once each turn.

Notion Rain

Surveil 2, then draw two cards. Notion Rain deals 2 damage to you. (To surveil 2, look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Negate

Getting

Brainstealer Dragon

Flying
At the beginning of your end step, exile the top card of each opponent's library. You may play those cards for as long as they remain exiled. If you cast a spell this way, you may spend mana as though it were mana of any color to cast it.
Whenever a nonland permanent an opponent owns enters the battlefield under your control, they lose life equal to its mana value.

Scry 1. (Look at the top card of your library. You may put that card on the bottom.)
Draw a card.

Power Word Kill

Destroy target non-Angel, non-Demon, non-Devil, non-Dragon creature.

Silumgar's Scorn

As an additional cost to cast this spell, you may reveal a Dragon card from your hand.
Counter target spell unless its controller pays {1}. If you revealed a Dragon card or controlled a Dragon as you cast this spell, counter that spell instead.

Crux of Fate

Choose one —
• Destroy all Dragon creatures.
• Destroy all non-Dragon creatures.

Dismal Backwater

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {U} or {B}.

Worn Powerstone

Worn Powerstone enters tapped.
{T}: Add {C}{C}.

Deathbringer Regent

Flying
When Deathbringer Regent enters, if you cast it from your hand and there are five or more other creatures on the battlefield, destroy all other creatures.

Hoarding Broodlord

Convoke
Flying
When Hoarding Broodlord enters, search your library for a card, exile it face down, then shuffle. For as long as that card remains exiled, you may play it.
Spells you cast from exile have convoke.

Maestros Theater

When Maestros Theater enters, sacrifice it. When you do, search your library for a basic Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle and you gain 1 life.

Ambition's Cost

You draw three cards and you lose 3 life.

Leaden Myr

Feed the Swarm

Destroy target creature or enchantment an opponent controls. You lose life equal to that permanent's mana value.

Dimir Guildgate

This land enters tapped.
{T}: Add {U} or {B}.

Swamp

Island

Thrummingbird

Flying
Whenever Thrummingbird deals combat damage to a player, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Acid-Spewer Dragon

Flying, deathtouch
Megamorph {5}{B}{B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)
When Acid-Spewer Dragon is turned face up, put a +1/+1 counter on each other Dragon creature you control.

Black Dragon

Flying
Acid Breath — When Black Dragon enters, target creature an opponent controls gets -3/-3 until end of turn.

Treasure Cruise

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Draw three cards.

Decree of Pain

Destroy all creatures. They can't be regenerated. Draw a card for each creature destroyed this way.
Cycling {3}{B}{B} ({3}{B}{B}, Discard this card: Draw a card.)
When you cycle Decree of Pain, all creatures get -2/-2 until end of turn.

Capsizing Wave

Return target creature to its owner's hand. (Then exile this card. You may cast the creature later from exile.)

Sword Coast Serpent

Sword Coast Serpent can't be blocked as long as you've cast a noncreature spell this turn.

Sword Coast Serpent // Capsizing Wave

Hidetsugu and Kairi

Flying
When Hidetsugu and Kairi enters, draw three cards, then put two cards from your hand on top of your library in any order.
When Hidetsugu and Kairi dies, exile the top card of your library. Target opponent loses life equal to its mana value. If it's an instant or sorcery card, you may cast it without paying its mana cost.

Renari, Merchant of Marvels

You may cast Dragon spells and artifact spells as though they had flash.
Choose a Background (You can have a Background as a second commander.)

Shimmer Dragon

Flying
As long as you control four or more artifacts, Shimmer Dragon has hexproof. (It can't be the target of spells or abilities your opponents control.)
Tap two untapped artifacts you control: Draw a card.

Teferi's Talent

Enchant planeswalker
Enchanted planeswalker has "[−12]: You get an emblem with 'You may activate loyalty abilities of planeswalkers you control on any player's turn any time you could cast an instant.'"
Whenever you draw a card, put a loyalty counter on enchanted planeswalker.

Firemind Vessel

Firemind Vessel enters tapped.
{T}: Add two mana of different colors.

Kaya's Ghostform

Enchant creature or planeswalker you control
When enchanted permanent dies or is put into exile, return that card to the battlefield under your control.

Bladewing's Thrall

Bladewing's Thrall has flying as long as you control a Dragon.
When a Dragon enters, you may return Bladewing's Thrall from your graveyard to the battlefield.

Lapis Orb of Dragonkind

{T}: Add {U}. When you spend this mana to cast a Dragon creature spell, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Icefall Regent

Flying
When Icefall Regent enters, tap target creature an opponent controls. That creature doesn't untap during its controller's untap step for as long as you control Icefall Regent.
Spells your opponents cast that target Icefall Regent cost {2} more to cast.

Astral Cornucopia

Astral Cornucopia enters with X charge counters on it.
{T}: Choose a color. Add one mana of that color for each charge counter on Astral Cornucopia.

Silumgar, the Drifting Death

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

Exotic Orchard

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

Dimir Signet

Aetherize

Return all attacking creatures to their owner's hand.

Wayfarer's Bauble

{2}, {T}, Sacrifice Wayfarer's Bauble: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Steel Hellkite

Flying
{2}: This creature gets +1/+0 until end of turn.
{X}: Destroy each nonland permanent with mana value X whose controller was dealt combat damage by this creature this turn. Activate only once each turn.

Dragonborn Looter

{1}, {T}: Draw a card, then discard a card.

Fellwar Stone

Underground River

{T}: Add {C}.
{T}: Add {U} or {B}. Underground River deals 1 damage to you.

Sol Ring

Myriad Landscape

Myriad Landscape enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Juvenile Mist Dragon

Flying
Confounding Clouds — When Juvenile Mist Dragon enters, for each opponent, tap up to one target creature that player controls. Each of those creatures doesn't untap during its controller's next untap step.

Arcane Signet

Dimir Aqueduct

Dimir Aqueduct enters tapped.
When Dimir Aqueduct enters, return a land you control to its owner's hand.
{T}: Add {U}{B}.

Draconic Lore

This spell costs {2} less to cast if you control a Dragon.
Draw three cards.

Settle the Score

Exile target creature. Put two loyalty counters on a planeswalker you control.

Mortuary Mire

Mortuary Mire enters tapped.
When Mortuary Mire enters, you may put target creature card from your graveyard on top of your library.
{T}: Add {B}.

Stonespeaker Crystal

{T}: Add {C}{C}.
{2}, {T}, Sacrifice Stonespeaker Crystal: Exile any number of target players' graveyards. Draw a card.

Waterfront District

Waterfront District enters tapped.
{T}: Add {U} or {B}.
{2}{U}{B}, {T}, Sacrifice Waterfront District: Draw a card.

Day of the Dragons

When Day of the Dragons enters, exile all creatures you control. Then create that many 5/5 red Dragon creature tokens with flying.
When Day of the Dragons leaves the battlefield, sacrifice all Dragons you control. Then return the exiled cards to the battlefield under your control.

Belltoll Dragon

Flying, hexproof
Megamorph {5}{U}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)
When Belltoll Dragon is turned face up, put a +1/+1 counter on each other Dragon creature you control.

Everflowing Chalice

Multikicker {2} (You may pay an additional {2} any number of times as you cast this spell.)
Everflowing Chalice enters with a charge counter on it for each time it was kicked.
{T}: Add {C} for each charge counter on Everflowing Chalice.

Dark Ritual

Sivitri, Dragon Master

+1: Until your next turn, creatures can't attack you or planeswalkers you control unless their controller pays 2 life for each of those creatures.
−3: Search your library for a Dragon card, reveal it, put it into your hand, then shuffle.
−7: Destroy all non-Dragon creatures.
Sivitri, Dragon Master can be your commander.

Go for the Throat

Clone

You may have Clone enter as a copy of any creature on the battlefield.

Mind Stone

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

Liliana's Talent

Enchant planeswalker
Enchanted planeswalker has "[−8]: Put all creature cards from all graveyards onto the battlefield under your control."
Whenever a creature deals damage to enchanted planeswalker, destroy that creature.

Palladium Myr

Portal Mage

Flash
When Portal Mage enters during the declare attackers step, you may reselect which player or permanent target attacking creature is attacking. (It can't attack its controller or their permanents.)

Sky Diamond

Resculpt

Exile target artifact or creature. Its controller creates a 4/4 blue and red Elemental creature token.

Charcoal Diamond

Charcoal Diamond enters tapped.
{T}: Add {B}.

Ornithopter of Paradise

Terramorphic Expanse

{T}, Sacrifice Terramorphic Expanse: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Ringsight

The Ring tempts you. Search your library for a card that shares a color with a legendary creature you control, reveal it, put it into your hand, then shuffle.

Phantasmal Dragon

Flying
When Phantasmal Dragon becomes the target of a spell or ability, sacrifice it.