msem-instigator

Whenever a creature an opponent controls dies, that player loses 1 life.
At the beginning of your end step, if an opponent lost 3 or more life this turn, create a 1/1 white Human creature token.
Fleeting {B} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

Flying
Mind's Contagion has haste as long as there are two or more creature cards in your graveyard.
Whenever Mind's Contagion deals combat damage to a player, until your next turn, it gains “Noncreature spells opponents cast cost an additional 2 life to cast.”

Other creatures you control get +2/+0.
Creatures your opponents control get -1/-1.
Fleeting {2}{B} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

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.)
When Opportunistic Beast enters, destroy up to one target creature that was dealt damage this turn.

Each player discards two cards. Then if there are four or more card types among cards in your graveyard, create two 1/1 white Human creature tokens.

Voracious 1 (As this enters, you may sacrifice an artifact or creature. If you do, it enters with a +1/+1 counter on it.)
Haste

Destroy target creature. Mill two cards.

When Poisonous Growth enters, create a 1/1 green Saproling creature token, then attach Poisonous Growth to it.
Equipped creature has deathtouch.
Equip {4}

Target player loses 3 life. Creatures you control gain menace until end of turn.

At the beginning of combat on your turn, tap Tinchor, put two +1/+1 counters on him, you draw a card, and you lose 1 life.
When Tinchor dies, put his counters on target Human you control.

Kicker—Sacrifice a creature. (You may sacrifice a creature in addition to any other costs as you cast this spell.)
You draw two cards and you lose 2 life. If this spell was kicked, you draw four cards and you lose 4 life instead.

Whenever one or more creatures you control deal combat damage to a player, that player discards a card. Then that player may discard another card. If they don't, create two 2/1 black Nightmare creature tokens with “This creature can't block.”
Fleeting {1}{B}{B} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

Deathtouch
When Vision Beyond the Waters enters, each player sacrifices two creatures other than this creature.

Choose any number —
• Each player loses X life.
• Each player discards X cards.
• Each player sacrifices X creatures.
• Each player sacrifices X lands.

Enchant creature
Enchanted creature gets +1/+0 for each card type among cards in your graveyard and has menace.
Fleeting {B} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

As an additional cost to cast this spell, sacrifice an artifact or creature.
Exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Double strike

You may exert Accursed Bear as it attacks. When you do, it gets +1/+0 and gains trample until end of turn. (An exerted creature won't untap during your next untap step.)

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (If you exert it, it will still untap for other players.)

Amid Flames deals 5 damage to target creature or planeswalker.
You may sacrifice a land. If you do, draw a card.

When Assurance of Finality enters, you may discard a card. If you do, draw two cards.
{1}, Sacrifice Assurance of Finality: Creatures you control gain haste until end of turn.

You may exert Awoken Elemental as it attacks. When you do, Awoken Elemental fights another target creature. (An exerted creature won't untap during your next untap step.)

Haste
You may exert Brash Charger as it attacks. When you do, creatures with power 1 or less can't block this turn. (An exerted creature won't untap during your next untap step.)

This spell can't be countered.
Burning Winds deals 3 damage to target creature or planeswalker. If that permanent would die this turn, exile it instead.

Carefree Performer can't be sacrificed.
You may exert Carefree Performer as it attacks. When you do, discard two cards, then draw two cards. (An exerted creature won't untap during your next untap step.)