msem-instigator

All creatures able to block Orphaned Nuckalavee do so.

At the beginning of your upkeep, scry 1, then you gain 1 life.

Enchant player
At the beginning of your upkeep, enchanted player loses 1 life.

Whenever Overgrowth Host attacks, germinate. Then creatures you control that are Saprolings or have counters on them gain trample until end of turn.
Saprolings you control get +1/+1.

(Transform this if it's not attached to a creature. Pay {G} as a sorcery to unattach it.)
Enchant creature you control
When this permanent transforms into Packbond Mount, move all +1/+1 counters from it to its rider.
Packbond Mount's rider gets +1/+1.
{2}{G}: Put a +1/+1 counter on Packbond Mount's rider.

Enchant creature
Enchanted creature gets +1/+1 and has “At the beginning of each end step, you gain 1 life.”

Enchant player
Whenever a creature enters under enchanted player's control, they lose 1 life.

Vigilance, deathtouch, menace

Whenever Power of Redemption attacks, choose one —
• Remove all -1/-1 counters from all creatures you control.
• Untap all creatures you control.

Prowess
Whenever Prodigal Spark is dealt damage, it deals that much damage to any target.

Flying, lifelink
Pay 5 life: Put target permanent card in a graveyard onto the battlefield under your control.

If Professor Haldean would leave the battlefield, exile him instead.
Whenever you cast a spell, you may untap Professor Haldean and another target permanent.
{T}: Professor Haldean deals 1 damage to each opponent.

Vigilance

Flying, haste
Whenever Pyrus, the Undying Flame attacks, add {R}{R}{R}{R}. You don't lose this mana as steps, phases, and turns end.
{1}{R}: Pyrus gets +1/+0 until end of turn.

Whenever you cast a noncreature spell, Rageborn Pyromancer gets +1/+1 until end of turn.
{1}{R}: Rageborn Pyromancer gets +1/+0 and gains flying until end of turn.

Flying

Legacy (You may play this side of this card only from your graveyard. Exile it if it would leave the battlefield or not resolve.)
At the beginning of your upkeep, you may return a creature card from your graveyard to your hand. If you do, you gain 2 life.

Whenever a creature dealt damage by Rei's Betrayer this turn dies, you gain life equal to that creature's toughness.

Rei, the Supplanter gets +1/+1 for each Forest you control.
At the beginning of each player's end step, if that player didn't play a land this turn, create a Forest token.

Legacy (You may play this side of this card only from your graveyard. Exile it if it would be put into a graveyard or not resolve.)
Target Warrior you control deals damage equal to its power to target creature an opponent controls.

[+1]: Create a 1/1 blue Elemental creature token with flying, then crystallize twice. (Put a +1/+1 counter on a creature you control or create a Treasure.)
[–3]: Exile target nonland permanent. As long as it's exiled, its owner may pay {W}{U}{B}{R}{G} as a sorcery to put it into their hand.
[–7]: You get an emblem with “Pay 1 life: Add one mana of any color.” Then you gain 100 life.

Whenever a creature enters, each opponent loses 1 life.

Whenever a creature dies, put a +1/+1 counter on Repository of Thoughts.
At the beginning of each combat, you may move a counter from Repository of Thoughts to target creature.

(Transforms from Ruined Theater.)
{T}: Add one mana of any color.

[+2]: Each player sacrifices a creature. Then each player who did creates a 1/1 white and black Spirit enchantment creature token.
[–X]: You may put an enchantment card with mana value X or less from your hand onto the battlefield.
[–6]: Shuffle, then reveal the top seven cards of your library. Put any number of enchantment cards from among them onto the battlefield. Shuffle the rest into your library.