msem-instigator

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.

Sacrifice Proud Lion: Counter target spell that targets you.
Ride {1}{W} ({1}{W}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Target player can't cast spells this turn.
Fabled {2}{W}{U} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that player.)

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 Queen Hannaru enters or attacks, put a +1/+1 counter on another target creature you control.
At the beginning of your upkeep, if there are four or more +1/+1 counters among creatures you control, you may transform Queen Hannaru.

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.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast a noncreature spell, draw a card.
At the beginning of your end step, if you have four or more cards in hand, transform Rahstahde.

Untap target creature. It gets +2/+2 and gains reach until end of turn.
Monument {3}{G} (You may cast this transformed from your graveyard for its monument cost. Exile it if it would leave the battlefield or not resolve.)

Flying

Exile the top three cards of your library. Until the end of your next turn, you may cast nonland cards exiled this way.
{3}{U}{R}: Return Reckless Experiment from your graveyard to the
battlefield tapped and transformed.

Refuse to Submit deals 3 damage to any target. If that target is an attacking creature, it deals 5 damage instead.

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.

Trample, haste
When Relonche Cavalry enters, other creatures you control get +1/+0 and gain trample and haste until end of turn.

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.

Flying, lifelink, haste
{W}{U}{B}{R}{G}, Exile Remi Amber, Slyten Specialist: Return Remi Amber to the battlefield transformed at the beginning of your next main phase.

[+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.