msem-instigator

Equipped creature gets +1/+1.
Equipped creature can't be blocked by more than one creature.
Equip {1}

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever an experience ability puts a +1/+1 counter on a creature you control, put a +1/+1 counter on that creature.

Enchant creature
Enchanted creature gets -2/-2.
Mirage—{B}, Discard a card. (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

When Battery Courier dies, lose 2 life.

{2}{R}: Target creature can't block Brimstone Courser this turn.
Ride {3}{R}{R} ({3}{R}{R}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Voracious 2 (As this enters, you may sacrifice up to two artifacts and/or creatures. This creature enters with that many +1/+1 counters on it.)
Trample
At the beginning of your end step, if a creature died under your control this turn, create a 1/1 green Saproling creature token.

Whenever one or more creatures attack you, you may put a -1/-1 counter on target creature.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast an instant or sorcery spell, up to one other target creature has base power and toughness 0/2 until end of turn.

Guardian of Dusk gets +X/+X, where X is the amount of life you've lost this turn.
When Guardian of Dusk has power 13 or greater, sacrifice it. If you do, you gain life equal to its power.

Whenever you discard a card, tap up to one target creature.

Creature cards in your graveyard have revive. The revive cost is equal to their mana cost. (Pay that creature's mana cost, Exile that card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Kicker {1}{R} (You may pay an additional {1}{R} as you cast this spell.)
Attacking creatures get +2/+0 until end of turn. Those creatures also gain first strike until end of turn if this spell was kicked.

Target creature gets +1/+0 and gains first strike until end of turn. Put a deathtouch counter on it.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Audition for black. (Create a 1/1 Construct Actor creature token, a Cleric Role giving 2/2 and lifelink, or a Warlock Role giving 2/1 and flying. Roles replace older ones.)
III — Until end of turn, if a creature you don't control would die, instead exile it and that creature's controller loses 2 life.
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{2}{B}, Sacrifice Determined Slayer: Exile up to three target cards from target player's graveyard. They lose that much life.

Sacrifice another creature: Blood Bairn gets +2/+2 until end of turn.

Koth's Retaliation deals 4 damage to target creature. When that creature dies this turn, exile its controller's graveyard.

Equipped creature gets +4/+2 and has first strike, vigilance, and trample.
Equip {3}

Enchant creature
When Chords of Order enters, put a +1/+1 counter on enchanted creature.
Whenever enchanted creature attacks, tap up to one target creature without a +1/+1 counter on it, then untap up to one target creature with a +1/+1 counter on it.

Counter target spell. Draw a card, then discard a card.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Remove a +1/+1 counter from Kor Skyknight: It gains flying until end of turn.

For each creature that's attacking you or a planeswalker you control, create a 1/1 blue Bird creature token with flying.

Choose target creature you don't control. When that creature dies this turn, draw a card. Target creature you control fights that creature.

For each creature, its owner puts it on the top or bottom of their library.

Flash
Flying
Once during each of your opponent's turns, when you cast a spell, you may pay {1}{U/R}. If you do, copy it. You may choose new targets for the copy. (If it's a permanent spell, the copy becomes a token.)