Obeka, Splitter of Seconds

Menace
Whenever Obeka, Splitter of Seconds deals combat damage to a player, you get that many additional upkeep steps after this phase.

Thrill of Possibility

As an additional cost to cast this spell, discard a card.
Draw two cards.

Replicating Ring

{T}: Add one mana of any color.
At the beginning of your upkeep, put a night counter on Replicating Ring. Then if it has eight or more night counters on it, remove all of them and create eight colorless snow artifact tokens named Replicated Ring with "{T}: Add one mana of any color."

Fellwar Stone

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

Rousing Refrain

Add {R} for each card in target opponent's hand. Until end of turn, you don't lose this mana as steps and phases end. Exile Rousing Refrain with three time counters on it.
Suspend 3—{1}{R} (Rather than cast this card from your hand, you may pay {1}{R} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Honden of Night's Reach

At the beginning of your upkeep, target opponent discards a card for each Shrine you control.

Wildfire Devils

When Wildfire Devils enters and at the beginning of your upkeep, choose a player at random. That player exiles an instant or sorcery card from their graveyard. Copy that card. You may cast the copy without paying its mana cost.

Court of Ambition

When Court of Ambition enters, you become the monarch.
At the beginning of your upkeep, each opponent loses 3 life unless they discard a card. If you're the monarch, instead each opponent loses 6 life unless they discard two cards.

Bedevil

Destroy target artifact, creature, or planeswalker.

Karlach, Fury of Avernus

Whenever you attack, if it's the first combat phase of the turn, untap all attacking creatures. They gain first strike until end of turn. After this phase, there is an additional combat phase.
Choose a Background (You can have a Background as a second commander.)

Psychotic Fury

Target multicolored creature gains double strike until end of turn.
Draw a card.

The Key to the Vault

Whenever equipped creature deals combat damage to a player, look at that many cards from the top of your library. You may exile a nonland card from among them. Put the rest on the bottom of your library in a random order. You may cast the exiled card without paying its mana cost.
Equip {2}{U}

Strix Serenade

Counter target artifact, creature, or planeswalker spell. Its controller creates a 2/2 blue Bird creature token with flying.

Festering March

Creatures your opponents control get -1/-1 until end of turn. Exile Festering March with three time counters on it.
Suspend 3—{2}{B} (Rather than cast this card from your hand, you may pay {2}{B} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)

Nightscape Familiar

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

Grenzo, Havoc Raiser

Whenever a creature you control deals combat damage to a player, choose one —
• Goad target creature that player controls.
• Exile the top card of that player's library. Until end of turn, you may cast that card and you may spend mana as though it were mana of any color to cast that spell.

Shadow of the Second Sun

Enchant player
At the beginning of enchanted player's second main phase, there is an additional beginning phase after this phase. (The end step happens after the added untap, upkeep, and draw steps.)

Embercleave

Flash
This spell costs {1} less to cast for each attacking creature you control.
When Embercleave enters, attach it to target creature you control.
Equipped creature gets +1/+1 and has double strike and trample.
Equip {3}

Relentless Assault

Untap all creatures that attacked this turn. After this main phase, there is an additional combat phase followed by an additional main phase.

Mechanized Production

Enchant artifact you control
At the beginning of your upkeep, create a token that's a copy of enchanted artifact. Then if you control eight or more artifacts with the same name as one another, you win the game.

Ring of Evos Isle

{2}: Equipped creature gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)
At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's blue.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Unexpected Windfall

As an additional cost to cast this spell, discard a card.
Draw two cards and create two Treasure tokens. (They're artifacts with "{T}, Sacrifice this artifact: Add one mana of any color.")

Sphinx of the Second Sun

Flying
At the beginning of your second main phase, there is an additional beginning phase after this phase. (The beginning phase includes the untap, upkeep, and draw steps.)

Plargg and Nassari

At the beginning of your upkeep, each player exiles cards from the top of their library until they exile a nonland card. An opponent chooses a nonland card exiled this way. You may cast up to two spells from among the other cards exiled this way without paying their mana costs.

Aggravated Assault

{3}{R}{R}: Untap all creatures you control. After this main phase, there is an additional combat phase followed by an additional main phase. Activate only as a sorcery.

The Ninth Doctor

Haste
Into the TARDIS — Whenever The Ninth Doctor becomes untapped during your untap step, you get an additional upkeep step after this step.

Arcane Signet

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

Counterspell

Jhoira of the Ghitu

{2}, Exile a nonland card from your hand: Put four time counters on the exiled card. If it doesn't have suspend, it gains suspend. (At the beginning of your upkeep, remove a time counter from that card. When the last is removed, you may cast it without paying its mana cost. If it's a creature, it has haste.)

Lizard Blades

Double strike
Equipped creature has double strike.
Reconfigure {2} ({2}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Honden of Seeing Winds

At the beginning of your upkeep, draw a card for each Shrine you control.

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.

Withengar Unbound

Flying, intimidate, trample (A creature with intimidate can't be blocked except by artifact creatures and/or creatures that share a color with it.)
Whenever a player loses the game, put thirteen +1/+1 counters on Withengar Unbound.

Elbrus, the Binding Blade

Equipped creature gets +1/+0.
When equipped creature deals combat damage to a player, unattach Elbrus, the Binding Blade, then transform it.
Equip {1}

Elbrus, the Binding Blade // Withengar Unbound

Generous Plunderer

Menace
At the beginning of your upkeep, you may create a Treasure token. When you do, target opponent creates a tapped Treasure token.
Whenever Generous Plunderer attacks, it deals damage to defending player equal to the number of artifacts they control.

Ornithopter of Paradise

Damnation

Destroy all creatures. They can't be regenerated.

Dark Ritual

Curse of the Cabal

Target player sacrifices half the permanents they control, rounded down.
Suspend 2—{2}{B}{B} (Rather than cast this card from your hand, you may pay {2}{B}{B} and exile it with two time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
At the beginning of each player's upkeep, if Curse of the Cabal is suspended, that player may sacrifice a permanent. If the player does, put two time counters on Curse of the Cabal.

Rakdos Charm

Choose one —
• Exile target player's graveyard.
• Destroy target artifact.
• Each creature deals 1 damage to its controller.

Goro-Goro, Disciple of Ryusei

{R}: Creatures you control gain haste until end of turn.
{3}{R}{R}: Create a 5/5 red Dragon Spirit creature token with flying. Activate only if you control an attacking modified creature. (Equipment, Auras you control, and counters are modifications.)

Solemn Simulacrum

When Solemn Simulacrum enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When Solemn Simulacrum dies, you may draw a card.

Faerie Mastermind

Flash
Flying
Whenever an opponent draws their second card each turn, you draw a card.
{3}{U}: Each player draws a card.

Big Score

Whispersilk Cloak

Equipped creature can't be blocked and has shroud. (It can't be the target of spells or abilities.)
Equip {2}

Profane Tutor

Suspend 2—{1}{B} (Rather than cast this card from your hand, pay {1}{B} and exile it with two time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
Search your library for a card, put that card into your hand, then shuffle.

Wyll's Reversal

Choose target spell or ability with one or more targets. Roll a d20 and add the greatest power among creatures you control.
1—14 | You may choose new targets for that spell or ability.
15+ | You may choose new targets for that spell or ability. Then copy it. You may choose new targets for the copy.

Court of Ire

When Court of Ire enters, you become the monarch.
At the beginning of your upkeep, Court of Ire deals 2 damage to any target. If you're the monarch, it deals 7 damage instead.

Injury

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Injury deals 2 damage to target creature and 2 damage to target player or planeswalker.

Insult

Damage can't be prevented this turn. If a source you control would deal damage this turn, it deals double that damage instead.

Insult // Injury

Silver Shroud Costume

Flash
When Silver Shroud Costume enters, attach it to target creature you control. That creature gains shroud until end of turn. (It can't be the target of spells or abilities.)
Equipped creature can't be blocked.
Equip {3}

Shadow Rift

Target creature gains shadow until end of turn. (It can block or be blocked by only creatures with shadow.)
Draw a card.

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Great Train Heist

Spree (Choose one or more additional costs.)
+ {2}{R} — Untap all creatures you control. If it's your combat phase, there is an additional combat phase after this phase.
+ {2} — Creatures you control get +1/+0 and gain first strike until end of turn.
+ {R} — Choose target opponent. Whenever a creature you control deals combat damage to that player this turn, create a tapped Treasure token.

Delina, Wild Mage

Whenever Delina, Wild Mage attacks, choose target creature you control, then roll a d20.
1—14 | Create a tapped and attacking token that's a copy of that creature, except it's not legendary and it has "At end of combat, exile this creature."
15—20 | Create one of those tokens. You may roll again.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Creeping Bloodsucker

At the beginning of your upkeep, Creeping Bloodsucker deals 1 damage to each opponent. You gain life equal to the damage dealt this way.

Negate

Compulsive Research

Target player draws three cards. Then that player discards two cards unless they discard a land card.

Quakebringer

Your opponents can't gain life.
At the beginning of your upkeep, Quakebringer deals 2 damage to each opponent. This ability triggers only if Quakebringer is on the battlefield or if Quakebringer is in your graveyard and you control a Giant.
Foretell {2}{R}{R}

Colossus Hammer

Equipped creature gets +10/+10 and loses flying.
Equip {8} ({8}: Attach to target creature you control. Equip only as a sorcery.)

Pardic Dragon

Flying
{R}: Pardic Dragon gets +1/+0 until end of turn.
Suspend 2—{R}{R}
Whenever an opponent casts a spell, if Pardic Dragon is suspended, that player may put a time counter on Pardic Dragon.

Dragonmaster Outcast

At the beginning of your upkeep, if you control six or more lands, create a 5/5 red Dragon creature token with flying.

Court of Locthwain

When Court of Locthwain enters, you become the monarch.
At the beginning of your upkeep, exile the top card of target opponent's library. You may play that card for as long as it remains exiled, and mana of any type can be spent to cast it. If you're the monarch, until end of turn, you may cast a spell from among cards exiled with Court of Locthwain without paying its mana cost.

Vandalblast

Destroy target artifact you don't control.
Overload {4}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Fell Mire

As Fell Mire enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {B}.

Fell the Profane

Fell the Profane // Fell Mire

Minas Morgul, Dark Fortress

Minas Morgul, Dark Fortress enters tapped.
{T}: Add {B}.
{3}{B}, {T}: Put a shadow counter on target creature. For as long as that creature has a shadow counter on it, it's a Wraith in addition to its other types. (A creature with shadow can block or be blocked by only creatures with shadow.)

Shivan Reef

{T}: Add {C}.
{T}: Add {U} or {R}. Shivan Reef deals 1 damage to you.

Command Tower

Shinka, the Bloodsoaked Keep

{T}: Add {R}.
{R}, {T}: Target legendary creature gains first strike until end of turn.

Arena of Glory

Arena of Glory enters tapped unless you control a Mountain.
{T}: Add {R}.
{R}, {T}, Exert Arena of Glory: Add {R}{R}. If that mana is spent on a creature spell, it gains haste until end of turn. (An exerted permanent won't untap during your next untap step.)

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Evolving Wilds

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

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.

Polluted Delta

{T}, Pay 1 life, Sacrifice Polluted Delta: Search your library for an Island or Swamp card, put it onto the battlefield, then shuffle.

Swamp

Island

Mountain

Artful Dodge

Target creature can't be blocked this turn.
Flashback {U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)