Biorhythm

Each player's life total becomes the number of creatures they control.

Sylvan Primordial

Reach
When Sylvan Primordial enters, for each opponent, destroy target noncreature permanent that player controls. For each permanent destroyed this way, search your library for a Forest card and put that card onto the battlefield tapped. Then shuffle.

Primeval Titan

Trample
Whenever Primeval Titan enters or attacks, you may search your library for up to two land cards, put them onto the battlefield tapped, then shuffle.

Erayo's Essence

Whenever an opponent casts their first spell each turn, counter that spell.

Erayo, Soratami Ascendant

Flying
Whenever the fourth spell of a turn is cast, flip Erayo, Soratami Ascendant.

Erayo, Soratami Ascendant // Erayo's Essence

Panoptic Mirror

Imprint — {X}, {T}: You may exile an instant or sorcery card with mana value X from your hand.
At the beginning of your upkeep, you may copy a card exiled with Panoptic Mirror. If you do, you may cast the copy without paying its mana cost.

Balance

Each player chooses a number of lands they control equal to the number of lands controlled by the player who controls the fewest, then sacrifices the rest. Players discard cards and sacrifice creatures the same way.

Rofellos, Llanowar Emissary

{T}: Add {G} for each Forest you control.

Braids, Cabal Minion

At the beginning of each player's upkeep, that player sacrifices an artifact, creature, or land of their choice.

Emrakul, the Aeons Torn

This spell can't be countered.
When you cast this spell, take an extra turn after this one.
Flying, protection from spells that are one or more colors, annihilator 6
When Emrakul, the Aeons Torn is put into a graveyard from anywhere, its owner shuffles their graveyard into their library.

Library of Alexandria

{T}: Add {C}.
{T}: Draw a card. Activate only if you have exactly seven cards in hand.

Recurring Nightmare

Sacrifice a creature, Return Recurring Nightmare to its owner's hand: Return target creature card from your graveyard to the battlefield. Activate only as a sorcery.

Flash

You may put a creature card from your hand onto the battlefield. If you do, sacrifice it unless you pay its mana cost reduced by {2}.

Sundering Titan

When Sundering Titan enters or leaves the battlefield, choose a land of each basic land type, then destroy those lands.

Coalition Victory

You win the game if you control a land of each basic land type and a creature of each color.

Iona, Shield of Emeria

Flying
As Iona, Shield of Emeria enters, choose a color.
Your opponents can't cast spells of the chosen color.