Archfiend of Ifnir

Flying
Whenever you cycle or discard another card, put a -1/-1 counter on each creature your opponents control.
Cycling {2} ({2}, Discard this card: Draw a card.)

Rakdos Signet

Vial Smasher the Fierce

Whenever you cast your first spell each turn, choose an opponent at random. Vial Smasher the Fierce deals damage equal to that spell's mana value to that player or a planeswalker that player controls.
Partner (You can have two commanders if both have partner.)

Kederekt Parasite

Whenever an opponent draws a card, if you control a red permanent, you may have Kederekt Parasite deal 1 damage to that player.

Villainous Wealth

Target opponent exiles the top X cards of their library. You may cast any number of spells with mana value X or less from among them without paying their mana costs.

Nekusar, the Mindrazer

At the beginning of each player's draw step, that player draws an additional card.
Whenever an opponent draws a card, Nekusar, the Mindrazer deals 1 damage to that player.

Putrefy

Destroy target artifact or creature. It can't be regenerated.

Gruul Signet

Venser's Journal

You have no maximum hand size.
At the beginning of your upkeep, you gain 1 life for each card in your hand.

Whirlpool Warrior

When Whirlpool Warrior enters the battlefield, shuffle the cards from your hand into your library, then draw that many cards.
{R}, Sacrifice Whirlpool Warrior: Each player shuffles the cards from their hand into their library, then draws that many cards.

Temple of Epiphany

Temple of Epiphany enters the battlefield tapped.
When Temple of Epiphany enters the battlefield, scry 1.
{T}: Add {U} or {R}.

Evolving Wilds

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

Fabled Passage

{T}, Sacrifice Fabled Passage: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle. Then if you control four or more lands, untap that land.

Niv-Mizzet, Parun

This spell can't be countered.
Flying
Whenever you draw a card, Niv-Mizzet, Parun deals 1 damage to any target.
Whenever a player casts an instant or sorcery spell, you draw a card.

Negate

Frontier Bivouac

Frontier Bivouac enters the battlefield tapped.
{T}: Add {G}, {U}, or {R}.

Grand Coliseum

Grand Coliseum enters the battlefield tapped.
{T}: Add {C}.
{T}: Add one mana of any color. Grand Coliseum deals 1 damage to you.

Demonic Tutor

Search your library for a card, put that card into your hand, then shuffle.

Echo of Eons

Each player shuffles their hand and graveyard into their library, then draws seven cards.
Flashback {2}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Stomping Ground

({T}: Add {R} or {G}.)
As Stomping Ground enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Blood Crypt

({T}: Add {B} or {R}.)
As Blood Crypt enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Psychosis Crawler

Psychosis Crawler's power and toughness are each equal to the number of cards in your hand.
Whenever you draw a card, each opponent loses 1 life.

Tolarian Winds

Discard all the cards in your hand, then draw that many cards.

Shadow of the Grave

Return to your hand all cards in your graveyard that you cycled or discarded this turn.

Forest

Fire Covenant

As an additional cost to cast this spell, pay X life.
Fire Covenant deals X damage divided as you choose among any number of target creatures.

Temple of Malady

Temple of Malady enters the battlefield tapped.
When Temple of Malady enters the battlefield, scry 1.
{T}: Add {B} or {G}.

Sol Ring

Swamp

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Comet Storm

Multikicker {1} (You may pay an additional {1} any number of times as you cast this spell.)
Choose any target, then choose another target for each time this spell was kicked. Comet Storm deals X damage to each of them.

Toothy, Imaginary Friend

Partner with Pir, Imaginative Rascal (When this creature enters the battlefield, target player may put Pir into their hand from their library, then shuffle.)
Whenever you draw a card, put a +1/+1 counter on Toothy, Imaginary Friend.
When Toothy leaves the battlefield, draw a card for each +1/+1 counter on it.

Umbral Mantle

Equipped creature has "{3}, {Q}: This creature gets +2/+2 until end of turn." ({Q} is the untap symbol.)
Equip {0}

Whirlpool Rider

When Whirlpool Rider enters the battlefield, shuffle the cards from your hand into your library, then draw that many cards.

Teferi's Puzzle Box

At the beginning of each player's draw step, that player puts the cards in their hand on the bottom of their library in any order, then draws that many cards.

Exotic Orchard

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

Dimir Signet

Nath of the Gilt-Leaf

At the beginning of your upkeep, you may have target opponent discard a card at random.
Whenever an opponent discards a card, you may create a 1/1 green Elf Warrior creature token.

Forgotten Creation

Skulk (This creature can't be blocked by creatures with greater power.)
At the beginning of your upkeep, you may discard all the cards in your hand. If you do, draw that many cards.

Breeding Pool

({T}: Add {G} or {U}.)
As Breeding Pool enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Windfall

Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

Long-Term Plans

Search your library for a card, then shuffle and put that card third from the top.

Izzet Signet

Gemstone Array

{2}: Put a charge counter on Gemstone Array.
Remove a charge counter from Gemstone Array: Add one mana of any color.

Terramorphic Expanse

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

Arcane Signet

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

Command Tower

Spellbook

The Locust God

Flying
Whenever you draw a card, create a 1/1 blue and red Insect creature token with flying and haste.
{2}{U}{R}: Draw a card, then discard a card.
When The Locust God dies, return it to its owner's hand at the beginning of the next end step.

Simic Signet

Drown in the Loch

Choose one —
• Counter target spell with mana value less than or equal to the number of cards in its controller's graveyard.
• Destroy target creature with mana value less than or equal to the number of cards in its controller's graveyard.

Savage Lands

Savage Lands enters the battlefield tapped.
{T}: Add {B}, {R}, or {G}.

Beacon of Tomorrows

Target player takes an extra turn after this one. Shuffle Beacon of Tomorrows into its owner's library.

Temple of Deceit

Temple of Deceit enters the battlefield tapped.
When Temple of Deceit enters the battlefield, scry 1.
{T}: Add {U} or {B}.

Overgrown Tomb

({T}: Add {B} or {G}.)
As Overgrown Tomb enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.

Opulent Palace

Opulent Palace enters the battlefield tapped.
{T}: Add {B}, {G}, or {U}.

Minamo, School at Water's Edge

{T}: Add {U}.
{U}, {T}: Untap target legendary permanent.

Leyline of Anticipation

If Leyline of Anticipation is in your opening hand, you may begin the game with it on the battlefield.
You may cast spells as though they had flash.

Counterspell

Goblin Electromancer

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

Niv-Mizzet, the Firemind

Flying
Whenever you draw a card, Niv-Mizzet, the Firemind deals 1 damage to any target.
{T}: Draw a card.

Darkwater Catacombs

Regrowth

Return target card from your graveyard to your hand.

Chasm Skulker

Whenever you draw a card, put a +1/+1 counter on Chasm Skulker.
When Chasm Skulker dies, create X 1/1 blue Squid creature tokens with islandwalk, where X is the number of +1/+1 counters on Chasm Skulker. (They can't be blocked as long as defending player controls an Island.)

Countersquall

Counter target noncreature spell. Its controller loses 2 life.

Temple of Malice

Temple of Malice enters the battlefield tapped.
When Temple of Malice enters the battlefield, scry 1.
{T}: Add {B} or {R}.

Temple of Abandon

Temple of Abandon enters the battlefield tapped.
When Temple of Abandon enters the battlefield, scry 1.
{T}: Add {R} or {G}.

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Temporal Cascade

Choose one —
• Each player shuffles their hand and graveyard into their library.
• Each player draws seven cards.
Entwine {2} (Choose both if you pay the entwine cost.)

Jace's Archivist

{U}, {T}: Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Pernicious Deed

{X}, Sacrifice Pernicious Deed: Destroy each artifact, creature, and enchantment with mana value X or less.

Molten Psyche

Each player shuffles the cards from their hand into their library, then draws that many cards.
Metalcraft — If you control three or more artifacts, Molten Psyche deals damage to each opponent equal to the number of cards that player has drawn this turn.

Sword of the Paruns

As long as equipped creature is tapped, tapped creatures you control get +2/+0.
As long as equipped creature is untapped, untapped creatures you control get +0/+2.
{3}: You may tap or untap equipped creature.
Equip {3}

Golgari Signet

Arjun, the Shifting Flame

Flying
Whenever you cast a spell, put the cards in your hand on the bottom of your library in any order, then draw that many cards.

Kodama's Reach

Mountain

Ancient Excavation

Draw cards equal to the number of cards in your hand, then discard a card for each card drawn this way.
Basic landcycling {2} ({2}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)

Dragon Mage

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

Cyclonic Rift

Return target nonland permanent you don't control to its owner's hand.
Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Reliquary Tower

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

Narset's Reversal

Copy target instant or sorcery spell, then return it to its owner's hand. You may choose new targets for the copy.

Temple of Mystery

Temple of Mystery enters the battlefield tapped.
When Temple of Mystery enters the battlefield, scry 1.
{T}: Add {G} or {U}.

Prismite

Oneirophage

Flying
Whenever you draw a card, put a +1/+1 counter on Oneirophage.

Diabolic Intent

As an additional cost to cast this spell, sacrifice a creature.
Search your library for a card, put that card into your hand, then shuffle.

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

Kydele, Chosen of Kruphix

{T}: Add {C} for each card you've drawn this turn.
Partner (You can have two commanders if both have partner.)

Whirlpool Drake

Flying
When Whirlpool Drake enters the battlefield, shuffle the cards from your hand into your library, then draw that many cards.
When Whirlpool Drake dies, shuffle the cards from your hand into your library, then draw that many cards.

Fate Unraveler

Whenever an opponent draws a card, Fate Unraveler deals 1 damage to that player.

Steam Vents

({T}: Add {U} or {R}.)
As Steam Vents enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.