The Rack

As The Rack enters the battlefield, choose an opponent.
At the beginning of the chosen player's upkeep, The Rack deals X damage to that player, where X is 3 minus the number of cards in their hand.

Armageddon Clock

At the beginning of your upkeep, put a doom counter on Armageddon Clock.
At the beginning of your draw step, Armageddon Clock deals damage equal to the number of doom counters on it to each player.
{4}: Remove a doom counter from Armageddon Clock. Any player may activate this ability but only during any upkeep step.

Naked Singularity

Cumulative upkeep {3} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
If tapped for mana, Plains produce {R}, Islands produce {G}, Swamps produce {W}, Mountains produce {U}, and Forests produce {B} instead of any other type.

Umbilicus

At the beginning of each player's upkeep, that player may pay 2 life. If they don't, they return a permanent they control to its owner's hand.

Crumbling Sanctuary

If damage would be dealt to a player, that player exiles that many cards from the top of their library instead.

Copper Tablet

At the beginning of each player's upkeep, Copper Tablet deals 1 damage to that player.

Paupers' Cage

At the beginning of each opponent's upkeep, if that player has two or fewer cards in hand, Paupers' Cage deals 2 damage to that player.

Rackling

At the beginning of each opponent's upkeep, Rackling deals X damage to that player, where X is 3 minus the number of cards in their hand.

Prototype Portal

Imprint — When Prototype Portal enters the battlefield, you may exile an artifact card from your hand.
{X}, {T}: Create a token that's a copy of the exiled card. X is the mana value of that card.

Gauntlet of Might

Red creatures get +1/+1.
Whenever a Mountain is tapped for mana, its controller adds an additional {R}.

Jester's Mask

Jester's Mask enters the battlefield tapped.
{1}, {T}, Sacrifice Jester's Mask: Target opponent puts the cards from their hand on top of their library. Search that player's library for that many cards. That player puts those cards into their hand, then shuffles.

Razormane Masticore

First strike (This creature deals combat damage before creatures without first strike.)
At the beginning of your upkeep, sacrifice Razormane Masticore unless you discard a card.
At the beginning of your draw step, you may have Razormane Masticore deal 3 damage to target creature.

Voodoo Doll

At the beginning of your upkeep, put a pin counter on Voodoo Doll.
At the beginning of your end step, if Voodoo Doll is untapped, destroy Voodoo Doll and it deals damage to you equal to the number of pin counters on it.
{X}{X}, {T}: Voodoo Doll deals damage equal to the number of pin counters on it to any target. X is the number of pin counters on Voodoo Doll.

Wheel of Torture

At the beginning of each opponent's upkeep, Wheel of Torture deals X damage to that player, where X is 3 minus the number of cards in their hand.

Thumbscrews

At the beginning of your upkeep, if you have five or more cards in hand, Thumbscrews deals 1 damage to target opponent or planeswalker.

Forethought Amulet

At the beginning of your upkeep, sacrifice Forethought Amulet unless you pay {3}.
If an instant or sorcery source would deal 3 or more damage to you, it deals 2 damage to you instead.

Mask of Intolerance

At the beginning of each player's upkeep, if there are four or more basic land types among lands that player controls, Mask of Intolerance deals 3 damage to that player.

Black Vise

As Black Vise enters the battlefield, choose an opponent.
At the beginning of the chosen player's upkeep, Black Vise deals X damage to that player, where X is the number of cards in their hand minus 4.

Scalding Tongs

At the beginning of your upkeep, if you have three or fewer cards in hand, Scalding Tongs deals 1 damage to target opponent or planeswalker.

Portcullis

Whenever a creature enters the battlefield, if there are two or more other creatures on the battlefield, exile that creature. Return that card to the battlefield under its owner's control when Portcullis leaves the battlefield.

Bubble Matrix

Prevent all damage that would be dealt to creatures.

Shrine of Limitless Power

At the beginning of your upkeep or whenever you cast a black spell, put a charge counter on Shrine of Limitless Power.
{4}, {T}, Sacrifice Shrine of Limitless Power: Target player discards a card for each charge counter on Shrine of Limitless Power.

Blood Clock

At the beginning of each player's upkeep, that player returns a permanent they control to its owner's hand unless they pay 2 life.

Lavaborn Muse

At the beginning of each opponent's upkeep, if that player has two or fewer cards in hand, Lavaborn Muse deals 3 damage to that player.

Nullstone Gargoyle

Flying
Whenever the first noncreature spell of a turn is cast, counter that spell.

Jinxed Idol

At the beginning of your upkeep, Jinxed Idol deals 2 damage to you.
Sacrifice a creature: Target opponent gains control of Jinxed Idol.

Hellfire Mongrel

At the beginning of each opponent's upkeep, if that player has two or fewer cards in hand, Hellfire Mongrel deals 2 damage to that player.

Damping Engine

A player who controls more permanents than each other player can't play lands or cast artifact, creature, or enchantment spells. That player may sacrifice a permanent for that player to ignore this effect until end of turn.

Noetic Scales

At the beginning of each player's upkeep, return to its owner's hand each creature that player controls with power greater than the number of cards in their hand.

Tangle Wire

Fading 4 (This artifact enters the battlefield with four fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
At the beginning of each player's upkeep, that player taps an untapped artifact, creature, or land they control for each fade counter on Tangle Wire.

Anvil of Bogardan

Players have no maximum hand size.
At the beginning of each player's draw step, that player draws an additional card, then discards a card.

Time Bomb

At the beginning of your upkeep, put a time counter on Time Bomb.
{1}, {T}, Sacrifice Time Bomb: Time Bomb deals damage equal to the number of time counters on it to each creature and each player.

Skullcage

At the beginning of each opponent's upkeep, Skullcage deals 2 damage to that player unless they have exactly three or exactly four cards in hand.

Ensnaring Bridge

Creatures with power greater than the number of cards in your hand can't attack.

Viseling

At the beginning of each opponent's upkeep, Viseling deals X damage to that player, where X is the number of cards in their hand minus 4.

Ghirapur Orrery

Each player may play an additional land on each of their turns.
At the beginning of each player's upkeep, if that player has no cards in hand, that player draws three cards.

Psychogenic Probe

Whenever a spell or ability causes a player to shuffle their library, Psychogenic Probe deals 2 damage to that player.

Barbed Wire

At the beginning of each player's upkeep, Barbed Wire deals 1 damage to that player.
{2}: Prevent the next 1 damage that would be dealt by Barbed Wire this turn.

Ebony Owl Netsuke

At the beginning of each opponent's upkeep, if that player has seven or more cards in hand, Ebony Owl Netsuke deals 4 damage to that player.

Misers' Cage

At the beginning of each opponent's upkeep, if that player has five or more cards in hand, Misers' Cage deals 2 damage to that player.

Sands of Time

Each player skips their untap step.
At the beginning of each player's upkeep, that player simultaneously untaps each tapped artifact, creature, and land they control and taps each untapped artifact, creature, and land they control.

Storm World

At the beginning of each player's upkeep, Storm World deals X damage to that player, where X is 4 minus the number of cards in their hand.