maybe

Flow of Knowledge

Draw a card for each Island you control, then discard two cards.

Contentious Plan

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

Coretapper

{T}: Put a charge counter on target artifact.
Sacrifice this creature: Put two charge counters on target artifact.

Pongify

Destroy target creature. It can't be regenerated. Its controller creates a 3/3 green Ape creature token.

Coalition Relic

{T}: Add one mana of any color.
{T}: Put a charge counter on this artifact.
At the beginning of your first main phase, remove all charge counters from this artifact. Add one mana of any color for each charge counter removed this way.

Spawning Pit

Sacrifice a creature: Put a charge counter on this artifact.
{1}, Remove two charge counters from this artifact: Create a 2/2 colorless Spawn artifact creature token.

Don't Have

Ledger Shredder

Flying
Whenever a player casts their second spell each turn, this creature connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on this creature.)

Arcane Signet

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

Marvin, Murderous Mimic

Marvin has all activated abilities of creatures you control that don't have the same name as this creature.

Ripples of Potential

Proliferate, then choose any number of permanents you control that had a counter put on them this way. Those permanents phase out. (To proliferate, choose any number of permanents and/or players, then give each another counter of each kind already there. Treat phased-out permanents and anything attached to them as though they don't exist until their controller's next turn.)

Drannith Ruins

{T}: Add {C}.
{2}, {T}: Put two +1/+1 counters on target non-Human creature that entered this turn.

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."

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.)

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.)

Dark Depths

Dark Depths enters with ten ice counters on it.
{3}: Remove an ice counter from Dark Depths.
When Dark Depths has no ice counters on it, sacrifice it. If you do, create Marit Lage, a legendary 20/20 black Avatar creature token with flying and indestructible.

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.)

Emry, Lurker of the Loch

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
When Emry enters, mill four cards.
{T}: Choose target artifact card in your graveyard. You may cast that card this turn. (You still pay its costs. Timing rules still apply.)

Delay

Counter target spell. If the spell is countered this way, exile it with three time counters on it instead of putting it into its owner's graveyard. If it doesn't have suspend, it gains suspend. (At the beginning of its owner's upkeep, they remove a time counter. When the last is removed, they may play it without paying its mana cost. If it's a creature, it has haste.)

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.

Hexavus

Flying
This creature enters with six +1/+1 counters on it.
{1}, Remove a +1/+1 counter from this creature: Put a flying counter on another target creature.
{1}, Remove a counter from another creature you control: Put a +1/+1 counter on this creature.

Sol Ring

Benthic Biomancer

{1}{U}: Adapt 1. (If this creature has no +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever one or more +1/+1 counters are put on this creature, draw a card, then discard a card.

Unctus, Grand Metatect

Other blue creatures you control have "Whenever this creature becomes tapped, draw a card, then discard a card."
Other artifact creatures you control get +1/+1.
{U/P}: Until end of turn, target creature you control becomes a blue artifact in addition to its other colors and types. Activate only as a sorcery. ({U/P} can be paid with either {U} or 2 life.)

Jace Reawakened

You can't cast Jace Reawakened during your first, second, or third turns of the game.
+1: Draw a card, then discard a card.
+1: You may exile a nonland card with mana value 3 or less from your hand. If you do, it becomes plotted.
−6: Until end of turn, whenever you cast a spell, copy it. You may choose new targets for the copy.

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.)

Faerie Conclave

This land enters tapped.
{T}: Add {U}.
{1}{U}: This land becomes a 2/1 blue Faerie creature with flying until end of turn. It's still a land.

Sapphire Medallion

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

Umezawa's Jitte

Whenever equipped creature deals combat damage, put two charge counters on Umezawa's Jitte.
Remove a charge counter from Umezawa's Jitte: Choose one —
• Equipped creature gets +2/+2 until end of turn.
• Target creature gets -1/-1 until end of turn.
• You gain 2 life.
Equip {2}

Serum Snare

Return target nonland permanent to its owner's hand. If that permanent had mana value 3 or less, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Geometric Nexus

Whenever a player casts an instant or sorcery spell, put a number of charge counters on this artifact equal to that spell's mana value.
{6}, {T}, Remove all charge counters from this artifact: Create a 0/0 green and blue Fractal creature token. Put X +1/+1 counters on it, where X is the number of charge counters removed this way.

Culling Dais

{T}, Sacrifice a creature: Put a charge counter on this artifact.
{1}, Sacrifice this artifact: Draw a card for each charge counter on this artifact.

Teferi, Temporal Pilgrim

Whenever you draw a card, put a loyalty counter on Teferi.
0: Draw a card.
−2: Create a 2/2 blue Spirit creature token with vigilance and "Whenever you draw a card, put a +1/+1 counter on this token."
−12: Target opponent chooses a permanent they control and returns it to its owner's hand. Then they shuffle each nonland permanent they control into its owner's library.

Tendo Ice Bridge

This land enters with a charge counter on it.
{T}: Add {C}.
{T}, Remove a charge counter from this land: Add one mana of any color.

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.)

Transmogrifying Wand

This artifact enters with three charge counters on it.
{1}, {T}, Remove a charge counter from this artifact: Destroy target creature. Its controller creates a 2/4 white Ox creature token. Activate only as a sorcery.

Tamiyo, the Moon Sage

+1: Tap target permanent. It doesn't untap during its controller's next untap step.
−2: Draw a card for each tapped creature target player controls.
−8: You get an emblem with "You have no maximum hand size" and "Whenever a card is put into your graveyard from anywhere, you may return it to your hand."

Island

Danny Pink

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
Creatures you control have "Whenever one or more counters are put on this creature for the first time each turn, draw a card."

Lost Jitte

Whenever equipped creature deals combat damage, put a charge counter on Lost Jitte.
Remove a charge counter from Lost Jitte: Choose one —
• Untap target land.
• Target creature can't block this turn.
• Put a +1/+1 counter on equipped creature.
Equip {1}

Chasm Skulker

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

Glen Elendra Archmage

Flying
{U}, Sacrifice this creature: Counter target noncreature spell.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

Enclave Cryptologist

Level up {1}{U} ({1}{U}: Put a level counter on this. Level up only as a sorcery.)
LEVEL 1-2
0/1
{T}: Draw a card, then discard a card.
LEVEL 3+
0/1
{T}: Draw a card.

Kiora Bests the Sea God

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create an 8/8 blue Kraken creature token with hexproof.
II — Tap all nonland permanents target opponent controls. They don't untap during their controller's next untap step.
III — Gain control of target permanent an opponent controls. Untap it.

Aphetto Alchemist

{T}: Untap target artifact or creature.
Morph {U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

The Great Synthesis

(As this Saga enters and after your draw step, add a lore counter.)
I — Draw cards equal to the number of cards in your hand. You have no maximum hand size for as long as you control this Saga.
II — Return all non-Phyrexian creatures to their owners' hands.
III — You may cast any number of spells from your hand without paying their mana costs. Exile this Saga, then return it to the battlefield (front face up).

Jin-Gitaxias

Ward {2}
Whenever you cast a noncreature spell with mana value 3 or greater, draw a card.
{3}{U}: Exile Jin-Gitaxias, then return it to the battlefield transformed under its owner's control. Activate only as a sorcery and only if you have seven or more cards in hand.

Jin-Gitaxias // The Great Synthesis

Suspend

Exile target creature and put two time counters on it. If it doesn't have suspend, it gains suspend. (At the beginning of its owner's upkeep, they remove a time counter. When the last is removed, they may play it without paying its mana cost. If it's a creature, it has haste.)

Jace Beleren

+2: Each player draws a card.
−1: Target player draws a card.
−10: Target player mills twenty cards.

Storm of Forms

When you cast this spell, copy it for each kind of counter among permanents you control. You may choose new targets for the copies.
Return target nonland permanent to its owner's hand.

Goldberry, River-Daughter

{T}: Move a counter of each kind not on Goldberry from another target permanent you control onto Goldberry.
{U}, {T}: Move one or more counters from Goldberry onto another target permanent you control. If you do, draw a card.

Living Breakthrough

Flying
Whenever you cast a spell, your opponents can't cast spells with the same mana value as that spell until your next turn.

Inventive Iteration

(As this Saga enters and after your draw step, add a lore counter.)
I — Return up to one target creature or planeswalker to its owner's hand.
II — Return an artifact card from your graveyard to your hand. If you can't, draw a card.
III — Exile this Saga, then return it to the battlefield transformed under your control.

Inventive Iteration // Living Breakthrough

Proft's Eidetic Memory

When Proft's Eidetic Memory enters, draw a card.
You have no maximum hand size.
At the beginning of combat on your turn, if you've drawn more than one card this turn, put X +1/+1 counters on target creature you control, where X is the number of cards you've drawn this turn minus one.

Saprazzan Cove

This land enters tapped.
{T}: Put a storage counter on this land.
{T}, Remove any number of storage counters from this land: Add {U} for each storage counter removed this way.

Lux Cannon

{T}: Put a charge counter on this artifact.
{T}, Remove three charge counters from this artifact: Destroy target permanent.

Mirrodin's Core

{T}: Add {C}.
{T}: Put a charge counter on this land.
{T}, Remove a charge counter from this land: Add one mana of any color.

Tome of Legends

This artifact enters with a page counter on it.
Whenever your commander enters or attacks, put a page counter on this artifact.
{1}, {T}, Remove a page counter from this artifact: Draw a card.

Idol of False Gods

{1}{C}, {T}: Create a 0/1 colorless Eldrazi Spawn creature token with "Sacrifice this token: Add {C}."
Whenever another Eldrazi you control dies, put a +1/+1 counter on this artifact.
As long as this artifact has eight or more +1/+1 counters on it, it's a 0/0 creature in addition to its other types and it has annihilator 2.

Deepglow Skate

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

Blast Zone

This land enters with a charge counter on it.
{T}: Add {C}.
{X}{X}, {T}: Put X charge counters on this land.
{3}, {T}, Sacrifice this land: Destroy each nonland permanent with mana value equal to the number of charge counters on this land.

Counterspell

Rapid Hybridization

Destroy target creature. It can't be regenerated. That creature's controller creates a 3/3 green Frog Lizard creature token.

The Bath Song

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Draw two cards, then discard a card.
III — Shuffle any number of target cards from your graveyard into your library. Add {U}{U}.

Titan Forge

{3}, {T}: Put a charge counter on this artifact.
{T}, Remove three charge counters from this artifact: Create a 9/9 colorless Golem artifact creature token.

Ioreth of the Healing House

{T}: Untap another target permanent.
{T}: Untap two other target legendary creatures.

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.)

Gavel of the Righteous

At the beginning of combat on your turn, put a charge counter on this Equipment.
Equipped creature gets +1/+1 for each counter on this Equipment.
As long as this Equipment has four or more counters on it, equipped creature has double strike.
Equip—Pay {3} or remove a counter from this Equipment.

Experimental Augury

Look at the top three cards of your library. Put one of them into your hand and the rest on the bottom of your library in any order. Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Gadwick's First Duel

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Create a Cursed Role token attached to up to one target creature. (If you control another Role on it, put that one into the graveyard. Enchanted creature is 1/1.)
II — Scry 2.
III — When you next cast an instant or sorcery spell with mana value 3 or less this turn, copy that spell. You may choose new targets for the copy.

Aven Courier

Flying
Whenever this creature attacks, choose a counter on a permanent you control. Put a counter of that kind on target permanent you control if it doesn't have a counter of that kind on it.

Reckoner Bankbuster

This Vehicle enters with three charge counters on it.
{2}, {T}, Remove a charge counter from this Vehicle: Draw a card. Then if there are no charge counters on this Vehicle, create a Treasure token and a 1/1 colorless Pilot creature token with "This token crews Vehicles as though its power were 2 greater."
Crew 3

Tyrite Sanctum

{T}: Add {C}.
{2}, {T}: Target legendary creature becomes a God in addition to its other types. Put a +1/+1 counter on it.
{4}, {T}, Sacrifice this land: Put an indestructible counter on target God.

Sting, the Glinting Dagger

Equipped creature gets +1/+1 and has haste.
At the beginning of each combat, untap equipped creature.
Equipped creature has first strike as long as it's blocking or blocked by a Goblin or Orc.
Equip {2}

Mystic Remora

Cumulative upkeep {1} (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.)
Whenever an opponent casts a noncreature spell, you may draw a card unless that player pays {4}.

Luxior, Giada's Gift

Equipped creature gets +1/+1 for each counter on it.
Equipped permanent isn't a planeswalker and is a creature in addition to its other types. (Loyalty abilities can still be activated.)
Equip planeswalker {1}
Equip {3}

The Mirari Conjecture

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — Return target instant card from your graveyard to your hand.
II — Return target sorcery card from your graveyard to your hand.
III — Until end of turn, whenever you cast an instant or sorcery spell, copy it. You may choose new targets for the copy.

Arcanis the Omnipotent

{T}: Draw three cards.
{2}{U}{U}: Return Arcanis to its owner's hand.

Iron Apprentice

This creature enters with a +1/+1 counter on it.
When this creature dies, if it had counters on it, put those counters on target creature you control.

Stonecoil Serpent

Reach, trample, protection from multicolored
This creature enters with X +1/+1 counters on it.

Ominous Seas

Whenever you draw a card, put a foreshadow counter on this enchantment.
Remove eight foreshadow counters from this enchantment: Create an 8/8 blue Kraken creature token.
Cycling {2} ({2}, Discard this card: Draw a card.)

Throne of Geth

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

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.)

Crystalline Giant

At the beginning of combat on your turn, choose a kind of counter at random that this creature doesn't have on it from among flying, first strike, deathtouch, hexproof, lifelink, menace, reach, trample, vigilance, and +1/+1. Put a counter of that kind on this creature.

As Foretold

At the beginning of your upkeep, put a time counter on this enchantment.
Once each turn, you may pay {0} rather than pay the mana cost for a spell you cast with mana value X or less, where X is the number of time counters on this enchantment.

Myojin of Cryptic Dreams

Myojin of Cryptic Dreams enters with an indestructible counter on it if you cast it from your hand.
Remove an indestructible counter from Myojin of Cryptic Dreams: Copy target permanent spell you control three times. (The copies become tokens.)

Malcolm, Alluring Scoundrel

Flash
Flying
Whenever Malcolm deals combat damage to a player, put a chorus counter on it. Draw a card, then discard a card. If there are four or more chorus counters on Malcolm, you may cast the discarded card without paying its mana cost.

Nesting Grounds

{T}: Add {C}.
{1}, {T}: Move a counter from target permanent you control onto another target permanent. Activate only as a sorcery.

Chrome Host Seedshark

Flying
Whenever you cast a noncreature spell, incubate X, where X is that spell's mana value. (Create an Incubator token with X +1/+1 counters on it and "{2}: Transform this token." It transforms into a 0/0 Phyrexian artifact creature.)

Saprazzan Skerry

This land enters tapped with two depletion counters on it.
{T}, Remove a depletion counter from this land: Add {U}{U}. If there are no depletion counters on this land, sacrifice it.

Skyship Plunderer

Flying
Whenever this creature deals combat damage to a player, for each kind of counter on target permanent or player, give that permanent or player another counter of that kind.

Power Conduit

{T}, Remove a counter from a permanent you control: Choose one —
• Put a charge counter on target artifact.
• Put a +1/+1 counter on target creature.

Ingenious Prodigy

Skulk (This creature can't be blocked by creatures with greater power.)
This creature enters with X +1/+1 counters on it.
At the beginning of your upkeep, if this creature has one or more +1/+1 counters on it, you may remove a +1/+1 counter from it. If you do, draw a card.

Zephyr Singer

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Flying, vigilance
When this creature enters, put a flying counter on each creature that convoked it.

Energy Chamber

At the beginning of your upkeep, choose one —
• Put a +1/+1 counter on target artifact creature.
• Put a charge counter on target noncreature artifact.

Sigil of Distinction

This Equipment enters with X charge counters on it.
Equipped creature gets +1/+1 for each charge counter on this Equipment.
Equip—Remove a charge counter from this Equipment.

Lost in the Maze

Flash
When this enchantment enters, tap X target creatures. Put a stun counter on each of those creatures you don't control. (If a permanent with a stun counter would become untapped, remove one from it instead.)
Tapped creatures you control have hexproof.

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.

Pyramid of the Pantheon

{2}, {T}: Add one mana of any color. Put a brick counter on this artifact.
{T}: Add three mana of any one color. Activate only if there are three or more brick counters on this artifact.

Orochi Hatchery

This artifact enters with X charge counters on it.
{5}, {T}: Create a 1/1 green Snake creature token for each charge counter on this artifact.