msem-instigator

You may cast a spell with mana value 3 or less from your hand without paying its mana cost. (Then exile this card. You may cast the creature later from exile.)

For each creature token you control, create a token that's a copy of that creature.

Flying
Whenever you attack, another target creature you control gains flying until end of turn.
Fleeting {U} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

{B}, {T}: Post a bounty on target permanent. (Put a bounty counter on that permanent. It has “When this permanent is put into a graveyard from the battlefield, each opponent draws a card” as long as it has a bounty counter on it.)
{B}, {T}, Pay 2 life: Destroy target creature with a bounty counter on it.

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Bounty Crusher has trample as long as it's being blocked by a marked creature.

Whenever a creature with a counter on it dies, create a Gold token. (It's an artifact with “Sacrifice this artifact: Add one mana of any color.”)

Harmony — Create a colorless artifact token named Lotus Petal with “{T}, Sacrifice this artifact: Add one mana of any color.”
When Bouquet Singer enters, harmonize. (Trigger up to one harmony of one permanent you control.)

Other Hounds you control get +1/+1.

Whenever Bourasan Street Watch attacks, you may pay {W}. If you do, Bourasan Street Watch gains indestructible until end of turn.

Enchant creature
Enchanted creature doesn't untap during its controller's untap step.

Gain control of target nonland permanent you don't control unless its controller has Bow or Burn deal X damage to them, where X is twice that permanent's mana value. If Bow or Burn was cast from a graveyard, repeat this process for each other nonland permanent they control.
Flashback {6}{R}{R}

You may activate Boxue and Ma'Long's loyalty abilities an additional time if you've cast two or more spells this turn.
[+1]: Scry 2.
[–2]: Exile the top two cards of your library. You may play one of them this turn. When you do, put the other card into your hand.
[–6]: Whenever you cast a spell this turn, copy it. You may choose new targets for the copy.

[+1]: Boxue deals 1 damage to each opponent. You may draw a card, then discard a card.
[–1]: Create a Treasure token.
[–5]: Copy the next spell you cast this turn. You may choose new targets for the copy. (A copied permanent spell becomes a token.)

Untap target creature you control. It gets +4/+4 and gains reach until end of turn.

Trample
{1}{G}: Brackish Kelpie gets +2/+2 until end of turn. Activate only once each turn.

{1}, Sacrifice Brackwater Scuttler: Draw a card.

When Braenid Nomad enters, draw two cards, then discard a card.

Target player discards two cards.
Fabled {3}{B}{B} (Then if you cast this for its fabled cost, put it onto the battlefield transformed attached to that player.)

Target opponent discards two cards. (Cast a copy of this spell once while this creature is on the battlefield.)

Counter target spell. Spells its controller casts cost {2} more to cast this turn.

{1}{B}: Regenerate Brainless Ghoul. (The next time this creature would be destroyed this turn, it isn't. Instead tap it, remove all damage from it, and remove it from combat.)

If you would draw a card, instead exile the top three cards of your library face down. You may look at those cards. Put a card exiled with Brainstorming Session into its owner's hand.
{X}{X}{U}, Sacrifice Brainstorming Session: Put X cards exiled with it into their owner's hand.

Gain control of target permanent. (Cast a copy of this spell once while this creature is on the battlefield.)