msem-instigator

Menace, haste
Whenever Tiger of the Drums attacks, choose one —
• Exile target opponent's graveyard.
• You draw a card and lose 1 life.
• Torment each opponent. (They lose 3 life unless they discard a card or sacrifice a nonland permanent.)

When Barbarian Hoarders enters, you may attach target Equipment you control to it.

{T}: Target player mills a card.
{4}, {T}, Exile Dusty Record: Target player shuffles their graveyard into their library.

Equipped creature gets +2/-1.
Equip {1}

Whenever equipped creature attacks, it gains deathtouch until end of turn.
Sacrifice Bandit's Dagger: Target player dealt damage by equipped creature this turn reveals their hand. You choose a nonland card from it. That player discards that card.
Equip {2}

As long as an opponent has two or fewer cards in their hand, Bonespitting Monstrosity gets +2/+2 and has menace and “Whenever Bonespitting Monstrosity attacks and isn't blocked, create a 1/1 black Skeleton creature token.”

{T}, Sacrifice a creature: Target player discards a card and loses 1 life. Activate only as a sorcery.

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
This creature can't be blocked by creatures with power 1 or less.

Exile target creature you control, then return that card to the battlefield under its owner's control. Create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

No more than one creature can attack each combat.
No more than one creature can block each combat.

You may have Unstable Impersonator enter as a copy of any creature on the battlefield chosen at random.

Flash
Enchant creature
When Arcane Anesthesia enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

This spell can't be countered.
Flying, haste
Mayu, the Endless Flow gets +2/+2 for each spell you've cast this turn.

If you casting a noncreature spell causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
Cycling {2} ({2}, Discard this card: Draw a card.)

Vigilance
Whenever Watchful Navigator crews a Vehicle, that Vehicle gets +1/+1 and gains vigilance until end of turn.

[+1]: Create a 1/1 blue Bird creature token with flying and haste.
[–1]: Creatures you control with flying get +1/+0 and gain vigilance until end of turn.
[–6]: Search your library for any number of creatures with flying and put them onto the battlefield. Shuffle your library.

Whenever Byway Bruiser enters or leaves the battlefield, you may have it deal 3 damage to any target.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast a noncreature spell, scry 1, then exile the top card of your library. Until end of turn, you may play that card.

Return target nonland permanent and all other permanents with the same name as that permanent to their owners' hands.
Draw a card.

This spell has flash as long as you control a permanent with flash.
Deactivate deals 5 damage to target tapped creature.

Dreamchaser Djinni attacks each combat if able.

Creatures you control gain first strike and vigilance until end of turn. Permutate. (You may remove a counter from a creature you control. If you do, put two +1/+1 counters on a different creature you control.)

Descended Fissure enters tapped.
{T}: Add {B} or {R}.
Morph {2} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

Enchant creature
Enchanted creature has flying and can only block creatures with flying.

When Sundering Arcanist enters, you may destroy target artifact or enchantment.
If you would draw a card, you may sacrifice a land and mill four cards instead. If you do, return Sundering Arcanist from your graveyard to your hand.