msem-instigator

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.)

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.

At the beginning of each end step, put a +1/+1 on Quickstep Ranger for each +1/+1
counter you've put on creatures under your control this turn.
Surpass {5}{G} ({5}{G}: Transform this creature. This costs {1} less to activate for each counter
on it. Activate only as a sorcery.)

Spells your opponents cast this turn cost {1} more to cast. (Then exile this card. You may cast the creature later from exile.)

Put a +1/+1 counter on each creature you control that entered this turn. (Then exile this card. You may cast the creature later from exile.)

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.

Haste
Whenever you cast a noncreature spell, put a +1/+1 counter on Rahstahde's Firefist. It gains menace until end of turn.

Haste
At the beginning of each end step, put a +1/+1 counter on Rahstahde's Swiftspear if you cast a noncreature spell this turn.
Surpass {5}{R} ({5}{R}: Transform this creature. This costs {1} less to activate for each counter on it. Activate only as a sorcery.)

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.

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.

Whenever Regretful Chronicler is dealt damage, put a +1/+1 counter on it. (It must survive the damage to get the counter.)
Surpass {5}{U} ({5}{U}: Transform this. This
costs 1 less to activate for each counter on it. Activate only as a sorcery.)

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.

Return target creature card with mana value 3 or less from your graveyard to the battlefield. You gain 3 life.

Lifelink
{W}{B}, {T}, Discard a card: Look at the top three cards of your library. You may reveal an enchantment card from among them and put it into your hand. Put the rest on the bottom of your library in any order.
When you have no cards in hand, exile Revela, then return her to the battlefield transformed under her owner's control.

[+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.