Rusting Golem

Fading 5 (This creature enters with five fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
Rusting Golem's power and toughness are each equal to the number of fade counters on it.

Deepglow Skate

When this creature enters, double the number of each kind of counter on any number of target permanents.

Inexorable Tide

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

Vorel of the Hull Clade

{G}{U}, {T}: Double the number of each kind of counter on target artifact, creature, or land.

Cloudskate

Flying
Fading 3 (This creature enters with three fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)

Thrummingbird

Flying
Whenever this creature 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.)

Command Tower

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

Parallax Tide

Fading 5 (This enchantment enters with five fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
Remove a fade counter from this enchantment: Exile target land.
When this enchantment leaves the battlefield, each player returns to the battlefield all cards they own exiled with it.

Everflowing Chalice

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

The Ozolith

Whenever a creature you control leaves the battlefield, if it had counters on it, put those counters on The Ozolith.
At the beginning of combat on your turn, if The Ozolith has counters on it, you may move all counters from The Ozolith onto target creature.

Simic Signet

The Millennium Calendar

Whenever you untap one or more permanents during your untap step, put that many time counters on The Millennium Calendar.
{2}, {T}: Double the number of time counters on The Millennium Calendar.
When there are 1,000 or more time counters on The Millennium Calendar, sacrifice it and each opponent loses 1,000 life.

Ezuri, Stalker of Spheres

When Ezuri enters, you may pay {3}. If you do, proliferate twice.
Whenever you proliferate, draw a card.

Evolution Sage

Landfall — Whenever a land you control enters, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Kathril, Aspect Warper

When Kathril enters, put a flying counter on any creature you control if a creature card in your graveyard has flying. Repeat this process for first strike, double strike, deathtouch, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance. Then put a +1/+1 counter on Kathril for each counter put on a creature this way.

Saproling Burst

Fading 7 (This enchantment enters with seven fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
Remove a fade counter from this enchantment: Create a green Saproling creature token. It has "This token's power and toughness are each equal to the number of fade counters on Saproling Burst."
When this enchantment leaves the battlefield, destroy all tokens created with this enchantment. They can't be regenerated.

Paradox Zone

This enchantment enters with a growth counter on it.
At the beginning of your end step, double the number of growth counters on this enchantment. Then create a 0/0 green and blue Fractal creature token. Put X +1/+1 counters on it, where X is the number of growth counters on this enchantment.

Vorinclex, Monstrous Raider

Trample, haste
If you would put one or more counters on a permanent or player, put twice that many of each of those kinds of counters on that permanent or player instead.
If an opponent would put one or more counters on a permanent or player, they put half that many of each of those kinds of counters on that permanent or player instead, rounded down.

Doubling Season

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.
If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Simic Ascendancy

{1}{G}{U}: Put a +1/+1 counter on target creature you control.
Whenever one or more +1/+1 counters are put on a creature you control, put that many growth counters on this enchantment.
At the beginning of your upkeep, if this enchantment has twenty or more growth counters on it, you win the game.

Herald of Secret Streams

Creatures you control with +1/+1 counters on them can't be blocked.

Kami of Whispered Hopes

If one or more +1/+1 counters would be put on a permanent you control, that many plus one +1/+1 counters are put on that permanent instead.
{T}: Add X mana of any one color, where X is this creature's power.

The First Tyrannic War

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — You may put a creature card from your hand onto the battlefield. If its mana cost contains {X}, it enters with a number of +1/+1 counters on it equal to the number of lands you control.
II, III — Double the number of each kind of counter on target creature you control.

Tangle Wire

Fading 4 (This artifact enters 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 this artifact.

Phyrexian Prowler

Fading 3 (This creature enters with three fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
Remove a fade counter from this creature: This creature gets +1/+1 until end of turn.

Astral Cornucopia

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

Indominus Rex, Alpha

As Indominus Rex enters, discard any number of creature cards. It enters with a flying counter on it if a card discarded this way has flying. The same is true for first strike, double strike, deathtouch, hexproof, haste, indestructible, lifelink, menace, reach, trample, and vigilance.
When Indominus Rex enters, draw a card for each counter on it.

Twenty-Toed Toad

Your maximum hand size is twenty.
Whenever you attack with two or more creatures, put a +1/+1 counter on Twenty-Toed Toad and draw a card.
Whenever Twenty-Toed Toad attacks, you win the game if there are twenty or more counters on it or you have twenty or more cards in hand.

Fathom Mage

Evolve (Whenever a creature you control enters, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.)
Whenever a +1/+1 counter is put on this creature, you may draw a card.

Woodripper

Fading 3 (This creature enters with three fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
{1}, Remove a fade counter from this creature: Destroy target artifact.

Tezzeret's Gambit

({U/P} can be paid with either {U} or 2 life.)
Draw two cards, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Rayami, First of the Fallen

If a nontoken creature would die, exile that card with a blood counter on it instead.
As long as an exiled creature card with a blood counter on it has flying, Rayami has flying. The same is true for first strike, double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, protection, reach, trample, and vigilance.

Gilder Bairn

{2}{G/U}, {Q}: Double the number of each kind of counter on target permanent. ({Q} is the untap symbol.)

Parallax Nexus

Fading 5 (This enchantment enters with five fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
Remove a fade counter from this enchantment: Target opponent exiles a card from their hand. Activate only as a sorcery.
When this enchantment leaves the battlefield, each player returns to their hand all cards they own exiled with it.

Karn's Bastion

{T}: Add {C}.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Replicating Ring

{T}: Add one mana of any color.
At the beginning of your upkeep, put a night counter on this artifact. 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."

Arna Kennerüd, Skycaptain

Flying, lifelink
Ward—Discard a card.
Whenever a modified creature you control attacks, double the number of each kind of counter on it. Then for each nontoken permanent attached to it, create a token that's a copy of that permanent attached to that creature.

Blastoderm

Shroud (This creature can't be the target of spells or abilities.)
Fading 3 (This creature enters with three fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)

Darksteel Reactor

Indestructible (Effects that say "destroy" don't destroy this artifact.)
At the beginning of your upkeep, you may put a charge counter on this artifact.
When this artifact has twenty or more charge counters on it, you win the game.

Contentious Plan

Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Draw a card.

Disciplined Duelist

Double strike
This creature enters with a shield counter on it. (If it would be dealt damage or destroyed, remove a shield counter from it instead.)

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.)

Parallax Wave

Fading 5 (This enchantment enters with five fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
Remove a fade counter from this enchantment: Exile target creature.
When this enchantment leaves the battlefield, each player returns to the battlefield all cards they own exiled with it.

Sol Ring

Unnatural Restoration

Return target permanent card from your graveyard to your hand. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Parallax Inhibitor

{1}, {T}, Sacrifice this artifact: Put a fade counter on each permanent with fading you control.

Skyshroud Ridgeback

Fading 2 (This creature enters with two fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)

Mutational Advantage

Permanents you control with counters on them gain hexproof and indestructible until end of turn. Prevent all damage that would be dealt to those permanents this turn. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Magistrate's Scepter

{4}, {T}: Put a charge counter on this artifact.
{T}, Remove three charge counters from this artifact: Take an extra turn after this one.

Tekuthal, Inquiry Dominus

Flying
If you would proliferate, proliferate twice instead.
{1}{U/P}{U/P}, Remove three counters from among other artifacts, creatures, and planeswalkers you control: Put an indestructible counter on Tekuthal. ({U/P} can be paid with either {U} or 2 life.)

Jolting Merfolk

Fading 4 (This creature enters with four fade counters on it. At the beginning of your upkeep, remove a fade counter from it. If you can't, sacrifice it.)
Remove a fade counter from this creature: Tap target creature.

Dreamtide Whale

Vanishing 2 (This creature enters with two time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
Whenever a player casts their second spell each turn, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)