The Ur-Dragon

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.

Mizzix of the Izmagnus

Whenever you cast an instant or sorcery spell with mana value greater than the number of experience counters you have, you get an experience counter.
Instant and sorcery spells you cast cost {1} less to cast for each experience counter you have.

Animar, Soul of Elements

Protection from white and from black
Whenever you cast a creature spell, put a +1/+1 counter on Animar, Soul of Elements.
Creature spells you cast cost {1} less to cast for each +1/+1 counter on Animar.

The Immortal Sun

Players can't activate planeswalkers' loyalty abilities.
At the beginning of your draw step, draw an additional card.
Spells you cast cost {1} less to cast.
Creatures you control get +1/+1.

Stinkdrinker Daredevil

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

Oketra's Monument

White creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, create a 1/1 white Warrior creature token with vigilance.

Cloud Key

As Cloud Key enters, choose artifact, creature, enchantment, instant, or sorcery.
Spells you cast of the chosen type cost {1} less to cast.

Stonybrook Banneret

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Merfolk spells and Wizard spells you cast cost {1} less to cast.

Spellwild Ouphe

Spells that target Spellwild Ouphe cost {2} less to cast.

Urza's Filter

Multicolored spells cost {2} less to cast.

Heartless Summoning

Creature spells you cast cost {2} less to cast.
Creatures you control get -1/-1.

Starfield Mystic

Enchantment spells you cast cost {1} less to cast.
Whenever an enchantment you control is put into a graveyard from the battlefield, put a +1/+1 counter on Starfield Mystic.

Thunderscape Familiar

First strike
Black spells and green spells you cast cost {1} less to cast.

Bontu's Monument

Black creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, each opponent loses 1 life and you gain 1 life.

Dream Chisel

Face-down creature spells you cast cost {1} less to cast.

Helm of Awakening

Ugin, the Ineffable

Colorless spells you cast cost {2} less to cast.
+1: Exile the top card of your library face down and look at it. Create a 2/2 colorless Spirit creature token. When that token leaves the battlefield, put the exiled card into your hand.
−3: Destroy target permanent that's one or more colors.

Herald of War

Flying
Whenever Herald of War attacks, put a +1/+1 counter on it.
Angel spells and Human spells you cast cost {1} less to cast for each +1/+1 counter on Herald of War.

Rhonas's Monument

Green creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, target creature you control gets +2/+2 and gains trample until end of turn.

Brighthearth Banneret

Elemental spells and Warrior spells you cast cost {1} less to cast.
Reinforce 1—{1}{R} ({1}{R}, Discard this card: Put a +1/+1 counter on target creature.)

God-Eternal Kefnet

Flying
You may reveal the first card you draw each turn as you draw it. Whenever you reveal an instant or sorcery card this way, copy that card and you may cast the copy. That copy costs {2} less to cast.
When God-Eternal Kefnet dies or is put into exile from the battlefield, you may put it into its owner's library third from the top.

Mistform Warchief

Creature spells you cast that share a creature type with Mistform Warchief cost {1} less to cast.
{T}: Mistform Warchief becomes the creature type of your choice until end of turn.

Baral, Chief of Compliance

Instant and sorcery spells you cast cost {1} less to cast.
Whenever a spell or ability you control counters a spell, you may draw a card. If you do, discard a card.

Undead Warchief

Zombie spells you cast cost {1} less to cast.
Zombie creatures you control get +2/+1.

Jhoira's Familiar

Flying
Historic spells you cast cost {1} less to cast. (Artifacts, legendaries, and Sagas are historic.)

Sunscape Familiar

Defender (This creature can't attack.)
Green spells and blue spells you cast cost {1} less to cast.

Goblin Warchief

Goblin spells you cast cost {1} less to cast.
Goblins you control have haste.

Myth Unbound

Your commander costs {1} less to cast for each time it's been cast from the command zone this game.
Whenever your commander is put into the command zone from anywhere, draw a card.

Pearl Medallion

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

Kinjalli's Caller

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

Urza's Incubator

As Urza's Incubator enters, choose a creature type.
Creature spells of the chosen type cost {2} less to cast.

Etherium Sculptor

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

Council of the Absolute

As Council of the Absolute enters, choose a noncreature, nonland card name.
Your opponents can't cast spells with the chosen name.
Spells with the chosen name you cast cost {2} less to cast.

Dragonspeaker Shaman

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

Ruby Medallion

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

Centaur Omenreader

As long as Centaur Omenreader is tapped, creature spells you cast cost {2} less to cast.

Morophon, the Boundless

Changeling (This card is every creature type.)
As Morophon, the Boundless 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.

Tezzeret, Master of the Bridge

Creature and planeswalker spells you cast have affinity for artifacts. (They cost {1} less to cast for each artifact you control.)
+2: Tezzeret, Master of the Bridge deals X damage to each opponent, where X is the number of artifacts you control. You gain X life.
−3: Return target artifact card from your graveyard to your hand.
−8: Exile the top ten cards of your library. Put all artifact cards from among them onto the battlefield.

Gargos, Vicious Watcher

Vigilance
Hydra spells you cast cost {4} less to cast.
Whenever a creature you control becomes the target of a spell, Gargos, Vicious Watcher fights up to one target creature you don't control.

Cheering Fanatic

Whenever Cheering Fanatic attacks, choose a card name. Spells with the chosen name cost {1} less to cast this turn.

Hazoret's Monument

Red creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, you may discard a card. If you do, draw a card.

Dragonlord's Servant

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

Eye of Ugin

Colorless Eldrazi spells you cast cost {2} less to cast.
{7}, {T}: Search your library for a colorless creature card, reveal it, put it into your hand, then shuffle.

Bosk Banneret

Treefolk spells and Shaman spells you cast cost {1} less to cast.

Long-Forgotten Gohei

Arcane spells you cast cost {1} less to cast.
Spirit creatures you control get +1/+1.

Primal Wellspring

(Transforms from Primal Amulet.)
{T}: Add one mana of any color. When that mana is spent to cast an instant or sorcery spell, copy that spell and you may choose new targets for the copy.

Primal Amulet

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, put a charge counter on Primal Amulet. Then if there are four or more charge counters on it, you may remove those counters and transform it.

Primal Amulet // Primal Wellspring

Arcane Melee

Instant and sorcery spells cost {2} less to cast.

Frogtosser Banneret

Haste
Goblin spells and Rogue spells you cast cost {1} less to cast.

Sapphire Medallion

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

Edgewalker

Cleric spells you cast cost {W}{B} less to cast. This effect reduces only the amount of colored mana you pay. (For example, if you cast a Cleric spell with mana cost {1}{W}, it costs {1} to cast.)

Elderwood Scion

Trample, lifelink
Spells you cast that target Elderwood Scion cost {2} less to cast.
Spells your opponents cast that target Elderwood Scion cost {2} more to cast.

Locket of Yesterdays

Spells you cast cost {1} less to cast for each card with the same name as that spell in your graveyard.

Saheeli, the Gifted

+1: Create a 1/1 colorless Servo artifact creature token.
+1: The next spell you cast this turn costs {1} less to cast for each artifact you control as you cast it.
−7: For each artifact you control, create a token that's a copy of it. Those tokens gain haste. Exile those tokens at the beginning of the next end step.
Saheeli, the Gifted can be your commander.

Will Kenrith

+2: Until your next turn, up to two target creatures each have base power and toughness 0/3 and lose all abilities.
−2: Target player draws two cards. Until your next turn, instant, sorcery, and planeswalker spells that player casts cost {2} less to cast.
−8: Target player gets an emblem with "Whenever you cast an instant or sorcery spell, copy it. You may choose new targets for the copy."
Partner with Rowan Kenrith
Will Kenrith can be your commander.

Krosan Drover

Creature spells you cast with mana value 6 or greater cost {2} less to cast.

Kefnet's Monument

Blue creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, target creature an opponent controls doesn't untap during its controller's next untap step.

Ragemonger

Minotaur spells you cast cost {B}{R} less to cast. This effect reduces only the amount of colored mana you pay. (For example, if you cast a Minotaur spell with mana cost {2}{R}, it costs {2} to cast.)

Mana Matrix

Instant and enchantment spells you cast cost {2} less to cast.

Goreclaw, Terror of Qal Sisma

Creature spells you cast with power 4 or greater cost {2} less to cast.
Whenever Goreclaw, Terror of Qal Sisma attacks, each creature you control with power 4 or greater gets +1/+1 and gains trample until end of turn.

Biomancer's Familiar

Activated abilities of creatures you control cost {2} less to activate. This effect can't reduce the mana in that cost to less than one mana.
{T}: The next time target creature adapts this turn, it adapts as though it had no +1/+1 counters on it.

Knight of the Stampede

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

Marauding Raptor

Creature spells you cast cost {1} less to cast.
Whenever another creature you control enters, Marauding Raptor deals 2 damage to it. If a Dinosaur is dealt damage this way, Marauding Raptor gets +2/+0 until end of turn.

Grand Arbiter Augustin IV

White spells you cast cost {1} less to cast.
Blue spells you cast cost {1} less to cast.
Spells your opponents cast cost {1} more to cast.

Ballyrush Banneret

Kithkin spells and Soldier spells you cast cost {1} less to cast.

Krosan Warchief

Beast spells you cast cost {1} less to cast.
{1}{G}: Regenerate target Beast.

Herald of Kozilek

Devoid (This card has no color.)
Colorless spells you cast cost {1} less to cast.

Battlefield Thaumaturge

Each instant and sorcery spell you cast costs {1} less to cast for each creature it targets.
Heroic — Whenever you cast a spell that targets Battlefield Thaumaturge, Battlefield Thaumaturge gains hexproof until end of turn.

Thornscape Familiar

Red spells and white spells you cast cost {1} less to cast.

Kadena, Slinking Sorcerer

The first face-down creature spell you cast each turn costs {3} less to cast.
Whenever a face-down creature you control enters, draw a card.

Foundry Inspector

Jace's Sanctum

Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast an instant or sorcery spell, scry 1.

Nightscape Familiar

Blue spells and red spells you cast cost {1} less to cast.
{1}{B}: Regenerate Nightscape Familiar.

Jet Medallion

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

Emerald Medallion

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

Stone Calendar

Oath of Ajani

When Oath of Ajani enters, put a +1/+1 counter on each creature you control.
Planeswalker spells you cast cost {1} less to cast.

Planar Gate

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

Stormscape Familiar

Flying
White spells and black spells you cast cost {1} less to cast.

Hardened Berserker

Whenever Hardened Berserker attacks, the next spell you cast this turn costs {1} less to cast.

Blood Funnel

Noncreature spells you cast cost {2} less to cast.
Whenever you cast a noncreature spell, counter that spell unless you sacrifice a creature.

Mycosynth Golem

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Artifact creature spells you cast have affinity for artifacts. (They cost {1} less to cast for each artifact you control.)

Daru Warchief

Soldier spells you cast cost {1} less to cast.
Soldier creatures you control get +1/+2.

Danitha Capashen, Paragon

First strike, vigilance, lifelink
Aura and Equipment spells you cast cost {1} less to cast.

Herald of the Pantheon

Enchantment spells you cast cost {1} less to cast.
Whenever you cast an enchantment spell, you gain 1 life.

Otepec Huntmaster

Dinosaur spells you cast cost {1} less to cast.
{T}: Target Dinosaur gains haste until end of turn.

Hero of Iroas

Aura spells you cast cost {1} less to cast.
Heroic — Whenever you cast a spell that targets Hero of Iroas, put a +1/+1 counter on Hero of Iroas.

Warden of Evos Isle

Flying
Creature spells with flying you cast cost {1} less to cast.

Unesh, Criosphinx Sovereign

Flying
Sphinx spells you cast cost {2} less to cast.
Whenever Unesh, Criosphinx Sovereign or another Sphinx you control enters, reveal the top four cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Semblance Anvil

Imprint — When Semblance Anvil enters, you may exile a nonland card from your hand.
Spells you cast that share a card type with the exiled card cost {2} less to cast.

Goblin Electromancer

Instant and sorcery spells you cast cost {1} less to cast.

Rakdos, Lord of Riots

You can't cast this spell unless an opponent lost life this turn.
Flying, trample
Creature spells you cast cost {1} less to cast for each 1 life your opponents have lost this turn.

Obscuring Aether

Face-down creature spells you cast cost {1} less to cast.
{1}{G}: Turn Obscuring Aether face down. (It becomes a 2/2 creature.)

Herald's Horn

As Herald's Horn enters, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.

Kethis, the Hidden Hand

Legendary spells you cast cost {1} less to cast.
Exile two legendary cards from your graveyard: Until end of turn, each legendary card in your graveyard gains "You may play this card from your graveyard."

Seal of the Guildpact

As Seal of the Guildpact enters, choose two colors.
Each spell you cast costs {1} less to cast for each of the chosen colors it is.