At the beginning of your end step, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
4 /
4
{2}{G}{W}
Captain Sisay
Legendary Creature - Human Soldier
{T}: Search your library for a legendary card, reveal that card, put it into your hand, then shuffle.
2 /
2
{4}
Crystalline Crawler
Artifact Creature - Construct
Converge -- Crystalline Crawler enters the battlefield with a +1/+1 counter on it for each color of mana spent to cast it.
Remove a +1/+1 counter from Crystalline Crawler: Add one mana of any color.
{T}: Put a +1/+1 counter on Crystalline Crawler.
1 /
1
{1}{W}{B}
Daxos the Returned
Legendary Creature - Zombie Soldier
Whenever you cast an enchantment spell, you get an experience counter.
{1}{W}{B}: Create a white and black Spirit enchantment creature token. It has "This creature's power and toughness are each equal to the number of experience counters you have."
2 /
2
{G}{W}
Eladamri's Call
Instant
Search your library for a creature card, reveal that card, put it into your hand, then shuffle.
{2}{G}
Evolution Sage
Creature - Elf Druid
Landfall -- Whenever a land enters the battlefield under your control, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
3 /
2
{X}{B}{B}
Exsanguinate
Sorcery
Each opponent loses X life. You gain life equal to the life lost this way.
{2}{G}{U}
Ezuri, Claw of Progress
Legendary Creature - Phyrexian Elf Warrior
Whenever a creature with power 2 or less enters the battlefield under your control, you get an experience counter.
At the beginning of combat on your turn, put X +1/+1 counters on another target creature you control, where X is the number of experience counters you have.
3 /
3
{2}{U}
Flux Channeler
Creature - Human Wizard
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.)
2 /
2
{5}
Golos, Tireless Pilgrim
Legendary Artifact Creature - Scout
When Golos, Tireless Pilgrim enters the battlefield, you may search your library for a land card, put that card onto the battlefield tapped, then shuffle.
{2}{W}{U}{B}{R}{G}: Exile the top three cards of your library. You may play them this turn without paying their mana costs.
3 /
5
{1}{W}
Grateful Apparition
Creature - Spirit
Flying
Whenever Grateful Apparition deals combat damage to a player or planeswalker, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
1 /
1
{X}{G}
Green Sun's Zenith
Sorcery
Search your library for a green creature card with mana value X or less, put it onto the battlefield, then shuffle. Shuffle Green Sun's Zenith into its owner's library.
{2}{U}
Guildpact Informant
Creature - Faerie Rogue
Flying
Whenever Guildpact Informant deals combat damage to a player or planeswalker, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
1 /
1
{3}{U}{U}
Inexorable Tide
Enchantment
Whenever you cast a spell, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
{2}{U}{R}
Jhoira, Weatherlight Captain
Legendary Creature - Human Artificer
Whenever you cast a historic spell, draw a card. (Artifacts, legendaries, and Sagas are historic.)
3 /
3
{2}{R}{W}
Kalemne, Disciple of Iroas
Legendary Creature - Giant Soldier
Double strike, vigilance
Whenever you cast a creature spell with mana value 5 or greater, you get an experience counter.
Kalemne, Disciple of Iroas gets +1/+1 for each experience counter you have.
3 /
3
--
Karn's Bastion
Land
{T}: Add {C}.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
{R}{W}{B}
Kelsien, the Plague
Legendary Creature - Human Assassin
Vigilance, haste
Kelsien, the Plague gets +1/+1 for each experience counter you have.
{T}: Kelsien deals 1 damage to target creature you don't control. When that creature dies this turn, you get an experience counter.
2 /
2
{4}{W}
Kenrith, the Returned King
Legendary Creature - Human Noble
{R}: All creatures gain trample and haste until end of turn.
{1}{G}: Put a +1/+1 counter on target creature.
{2}{W}: Target player gains 5 life.
{3}{U}: Target player draws a card.
{4}{B}: Put target creature card from a graveyard onto the battlefield under its owner's control.
5 /
5
{W}{B}{G}
Kethis, the Hidden Hand
Legendary Creature - Elf Advisor
Legendary spells you cast cost {1} less to cast.
Exile two legendary cards from your graveyard: Until end of turn, each legendary card in your graveyard gains "You may play this card from your graveyard."
3 /
4
{2}{B}{G}
Meren of Clan Nel Toth
Legendary Creature - Human Shaman
Whenever another creature you control dies, you get an experience counter.
At the beginning of your end step, choose target creature card in your graveyard. If that card's mana value is less than or equal to the number of experience counters you have, return it to the battlefield. Otherwise, put it into your hand.
3 /
4
{G}{U}
Merfolk Skydiver
Creature - Merfolk Mutant
Flying
When Merfolk Skydiver enters the battlefield, put a +1/+1 counter on target creature you control.
{3}{G}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
1 /
1
{3}{G}{W}
Mirari's Wake
Enchantment
Creatures you control get +1/+1.
Whenever you tap a land for mana, add one mana of any type that land produced.
{2}{U}{R}
Mizzix of the Izmagnus
Legendary Creature - Goblin Wizard
Whenever you cast an instant or sorcery spell with mana value greater than the number of experience counters you have, you get an experience counter.
Instant and sorcery spells you cast cost {1} less to cast for each experience counter you have.
2 /
2
{U}{U}
Muddle the Mixture
Instant
Counter target instant or sorcery spell.
Transmute {1}{U}{U} ({1}{U}{U}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)
{4}{G}{G}{G}
Nyxbloom Ancient
Enchantment Creature - Elemental
Trample
If you tap a permanent for mana, it produces three times as much of that mana instead.
5 /
5
{3}{G}{G}
Plaguemaw Beast
Creature - Phyrexian Beast
{T}, Sacrifice a creature: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
4 /
3
{5}{W}{B}
Primevals' Glorious Rebirth
Legendary Sorcery
(You may cast a legendary sorcery only if you control a legendary creature or planeswalker.)
Return all legendary permanent cards from your graveyard to the battlefield.
{2}{G}{G}{U}
Roalesk, Apex Hybrid
Legendary Creature - Human Mutant
Flying, trample
When Roalesk, Apex Hybrid enters the battlefield, put two +1/+1 counters on another target creature you control.
When Roalesk dies, proliferate, then proliferate again. (Choose any number of permanents and/or players, then give each another counter of each kind already there. Then do it again.)
4 /
5
{3}{G}{G}
Shared Summons
Instant
Search your library for up to two creature cards with different names, reveal them, put them into your hand, then shuffle.
{2}{W}
Sisay, Weatherlight Captain
Legendary Creature - Human Soldier
Sisay, Weatherlight Captain gets +1/+1 for each color among other legendary permanents you control.
{W}{U}{B}{R}{G}: Search your library for a legendary permanent card with mana value less than Sisay's power, put that card onto the battlefield, then shuffle.
2 /
2
{0}
Summoner's Pact
Instant
Search your library for a green creature card, reveal it, put it into your hand, then shuffle.
At the beginning of your next upkeep, pay {2}{G}{G}. If you don't, you lose the game.
{3}
Sword of Truth and Justice
Artifact - Equipment
Equipped creature gets +2/+2 and has protection from white and from blue.
Whenever equipped creature deals combat damage to a player, put a +1/+1 counter on a creature you control, then proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
Equip {2}
{1}{U}
Thrummingbird
Creature - Phyrexian Bird Horror
Flying
Whenever Thrummingbird 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.)
1 /
1
{X}{B}{B}
Torment of Hailfire
Sorcery
Repeat the following process X times. Each opponent loses 3 life unless that player sacrifices a nonland permanent or discards a card.
{3}{U}
Viral Drake
Creature - Phyrexian Drake
Flying
Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
{3}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
1 /
4
{G}
Worldly Tutor
Instant
Search your library for a creature card, reveal it, then shuffle and put the card on top.
{2}{B}{B}
Yawgmoth, Thran Physician
Legendary Creature - Human Cleric
Protection from Humans
Pay 1 life, Sacrifice another creature: Put a -1/-1 counter on up to one target creature and draw a card.
{B}{B}, Discard a card: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)