msem-instigator

Take an extra turn after this one. At the beginning of that turn's end step, sacrifice each land you control. Whenever you cast a spell during that turn, copy it. You may choose new targets for the copy.
Exile Futuretheft.

{16}, {T}: Time Cube gains “At the beginning of your end step, if it's not an extra turn, take three extra turns after this one” and loses this ability.

Whenever a creature you control dies, put a rot counter on Fester Swarm and you gain 1 life.
{B}{G}, Remove two or more rot counters from Fester Swarm: Create a 1/1 green Insect creature token, then put a +1/+1 counter on it for each rot counter removed this way.

Other creatures you control get +1/+1.
When Kotis, Promised General dies, you may return it to its owner's hand.

Reach
Whenever another creature you control dies, surveil 1.
{T}, Sacrifice a non-Spider creature: Create a 1/2 green Spider creature with reach.

Harness (You may tap a creature you control as you cast this spell. If you do, reduce this spell's mana cost by that creature's power.)
Search target opponent's library for a creature or planeswalker card and put it onto the battlefield under your control. That player shuffles.

Destroy target creature. Trigger a death knell of a permanent you control.

Flying
{U}: Ripclaw Drake gets +1/-1 until end of turn.

At the beginning of your upkeep, if each opponent controls more lands than you, search your library for a basic land card, reveal it, and put it into your hand, then shuffle.

Other nonland permanents enter tapped.
Your opponents can't activate abilities of tapped permanents.

Flying

If a creature would die, exile it instead with an ancestry counter on it.
Kahroba gets +X/+X, where X is the total power of creature cards exiled with ancestry counters on them.
At the beginning of your upkeep, if there are four or more cards exiled with ancestry counters on them, transform Kahroba.

Flying
When Mother of Owls dies, you may return target creature an opponent controls to its owner's hand.

Your life total becomes 0. Until an opponent's next turn, you can't lose the game, your opponents can't win the game, and you can't gain life.
Take an extra turn after this one.
Exile Buy Time.

Blessed Grounds enters tapped. When it enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Add {G} or {W}.

Whenever you lose 2 or more life during your turn, put two blood counters on Hemomancy.
{1}{B}, Remove X blood counters from Hemomancy: Return target creature card with mana value X from your graveyard to the battlefield.

Return target creature card from a graveyard to the battlefield. Then if that card wasn't put into a graveyard from the battlefield this turn, exile it.

Defender (This creature can't attack.)
Discard a card: Barge Engulfer can attack as though it didn't have defender until end of turn.

When Joyful Deviant enters or dies, it deals 1 damage to any target.

Flash
When Comforting Presence enters, return target spell with mana value 2 or less to its owner's hand.
Whenever an opponent casts their second spell each turn, draw a card.

As this permanent transforms into Velir, put four loyalty counters on it.
[+1]: Draw two cards, then discard two cards unless you discard a land card.
[–2]: Search your library for a multicolored card, reveal it, put it into your hand, then shuffle.
[–4]: Exile target permanent.

Exile X target permanents you control. Return them to the battlefield under your control at the beginning of the next end step.
Draw a card.

When Kaleidostone enters, draw a card.
{5}, {T}, Sacrifice Kaleidostone: Add {W}{U}{B}{R}{G}.

{T}: Add {C}.
Tap three differently named untapped Academies you control: Put a +1/+1 counter on target permanent. Activate only as a sorcery.

When Goldengrain Alseid enters, you may search your library for a basic Plains card, reveal it, put it into your hand, then shuffle.