msem-instigator

Target creature you control gains haste until end of turn. Return it to its owner's hand at the beginning of the next end step.

Whenever Ontarachie Hunter attacks, each opponent loses 1 life.
At the beginning of your end step, if an opponent has 10 or less life, transform Ontarachie Hunter.

Whenever Orphan Prodigy is dealt damage, it deals that much damage to target player.
Attain {4}{R} ({4}{R}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

All creatures able to block Orphaned Nuckalavee do so.

Out-of-Depth Amateur can't attack or block alone.
Attain {4}{R} ({4}{R}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

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.

Whenever a creature dies, Pakka, the Shadowcloak deals 1 damage to each opponent.

Sacrifice a creature: Pale Horse gets +2/+2 until end of turn.
Ride {B} ({B}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

When Paleolizard enters the battlefield, you may discard a card. When you do, return target card from your graveyard to your hand that shares a type with that card.

Flash
As long as Panya and exactly one other creature are attacking, both have flying.

Whenever Passionate Painter becomes untapped, you may discard a card. If you do, draw a card, then transform Passionate Painter.

Defender
Ascend {1}{W}{W} ({1}{W}{W}: Exile this creature, then return it to the battlefield transformed. Ascend only as a sorcery.)

When Paw Valley Pathfinder enters the battlefield, reveal the top card of your library. If it's a land card, draw a card.

{R}: Paw Valley Wildclaw gets +1/+0 until end of turn. Then if its power is exactly 4, add {R}{R}{R}.

Create two tapped Treasure tokens. (Then exile this card. You may cast the creature later from exile.)

At the beginning of your upkeep, each player discards a card. Then if a player has no cards in hand, you may transform Performer of Ambition.

{U}, {T}: Sacrifice any number of nontoken creatures. Create an X/X blue Horror creature token, where X is the total power of those creatures. Then if X is 4 or greater, you may transform Performer of Brilliance.

{1}{R}: Performer of Desire gets +1/+1 and gains menace until end of turn. Then if its power is 4 or greater, you may transform it.

{2}, {T}: You gain life equal to the number of colors among cards in your graveyard.
{W}{U}{B}{R}{G}: Transform Performer of Enlightenment.

{T}: Add {G}. When that mana is used to cast a spell with mana value 5 or greater, you may untap Performer of Growth and transform it.

Choose highest or lowest. Target opponent reveals their hand and discards a card with the chosen kind of mana value among the revealed nonland cards.

When Piruz, the Fourth Shah enters the battlefield, discard your hand. For each creature card discarded this way, create a 3/3 black Demon creature token with flying. For each other card discarded this way, you gain 3 life.
Monument {5}{B}{B} (You may cast this transformed from your graveyard for its monument cost. Exile it if it would leave the battlefield or not resolve.)

Deathtouch
Unveil {3}{B}{G} ({3}{B}{G}: Transform this. Unveil only as a sorcery.)