msem-instigator

{1}{U}{B}, Discard Karaja Hetegex: You may activate one of her loyalty abilities without paying its loyalty cost.
[–1]: Return target artifact, enchantment, or spell to its owner's hand.
[–1]: Target creature gets -2/-2 until end of turn.
[–1]: Scry 1, then draw a card.

Whenever you cast an instant or sorcery spell, Kederekt Deepdweller gains your choice of indestructible, lifelink, or menace until end of turn.
Whenever Kederekt Deepdweller deals combat damage to a player, you draw a card and that player discards a card.

Return target creature, instant, or sorcery card from your graveyard to your hand. Then exile Keep What Was Lost if it wasn't cast from your hand.
Acquiesce (If you cast this spell from your hand, exile it as it resolves. When one or more creatures you control deal combat damage to an opponent, you may cast this card from exile without paying its mana cost.)

Whenever you cast a spell from exile, copy that spell. You may choose new targets for the copy.
{B}, Discard a card: When you next cast a spell from your hand this turn, it gains rerun. Activate this ability only once each turn. (Exile it as it resolves if you cast it from your hand. Whenever a creature you control dies, you may cast that card from exile without paying its mana cost.)

[+1]: Create a 1/1 colorless Thopter artifact creature token with flying. It gains lifelink until your next turn.
[–1]: Sacrifice an artifact. If you do, draw two cards.
[–6]: Draw seven cards. Artifact spells you cast this turn cost {2} less to cast.

[+1]: Create a 1/1 white Warrior creature token. Put a menace counter on it.
[–2]: Draw a card for each tapped creature you control.
[–5]: You get an emblem with “Creature cards in your hand have ‘{1}{U}{B}, Reveal this card from your hand, Return an unblocked attacking creature you control to its owner's hand: Put this card onto the battlefield tapped and attacking.'”

Deathtouch
The first instant or sorcery spell with mana value 3 or less you cast each turn has siphon. (Each -1/-1 counter you put on your creatures up to their remaining toughness while casting this pays for {1}.)

Flash
Whenever a creature you control deals combat damage to a player, create a Treasure token, then exile the top card of that player's library. You may play cards exiled this way for as long as they remain exiled.

Flying, deathtouch

Deathtouch
Artifacts and creatures your opponents control have “At the beginning of your upkeep, you lose 1 life unless you tap this permanent and have an opponent gain control of it.”

[+1]: Move a counter from up to one target permanent onto another permanent that shares a type with it.
[–1]: Target creature gets -1/-3 until end of turn.
[–5]: Search target opponent's library for a creature or planeswalker card and put that card onto the battlefield under your control. Then that player shuffles.

Flash
Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)

Marinton Occultist can't block or be blocked.
Whenever one or more cards are put into a player's graveyard from their library, Marinton Occultist gets +1/+1 until end of turn.

When this creature enters, put a -1/-1 counter on a creature you control.
Whenever you put one or more -1/-1 counters on one or more creatures, surveil 2.

Menace
Whenever Masoh enters or attacks, each opponent that has more than four cards in hand discards cards equal to the difference. Then if you have fewer than four cards in hand, draw cards equal to the difference.

Whenever a player discards a card, you may draw a card and put a loyalty counter on Mei Liva, the Broken.
[0]: Target permanent's controller sacrifices it unless they discard two cards.
[–1]: Each opponent loses X life and you gain X life, where X is the number of cards in your hand.
[–3]: Target player chooses a card in their hand, then discards the rest.

[+1]: Search each player's graveyard, hand, and library for any number of cards with the same name as target nonbasic card in a graveyard and exile them. Then each player shuffles.
[–2]: Each player draws two cards, then each opponent exiles two cards at random from their hand.
[–5]: You may cast a card exiled with Mei Liva without paying its mana cost.

[+2]: Each opponent loses 2 life. Scry 2.
[–3]: Return target creature to its owner's hand. That player discards a card.
[–6]: You get an emblem with “Whenever a player discards a card, you may cast it without paying its mana cost.”

[+1]: Draw a card unless an opponent discards a card.
[–3]: Gain control of target creature until the end of your next turn.
[–6]: Choose up to four cards in graveyards. You may play those cards without paying their mana costs.

Whenever Memory of Fatalism dies or you cast a noncreature spell, each opponent loses 2 life and you gain 2 life.
{4}: Put Memory of Fatalism from your graveyard on top of your library.

Infiltrate (Whenever one or more attacking creatures you control aren't blocked, this creature gets +1/+1 until end of turn.)
Whenever Merciless Exiled deals combat damage to a player, scry 2.

Whenever one or more creatures deal combat damage to you, exile one of those creatures.
You may cast cards exiled with Merciless Mirror and may spend mana as though it were mana of any color to cast those spells.

Artifact spells you cast cost {1} less to cast.
{2}, Sacrifice an artifact: Target creature gains deathtouch until end of turn.

Counter target spell. Search its controller's library for a card with mana value X or less and cast it without paying its mana cost. Then that player shuffles.

[+2]: Target player exiles a card from their hand at random. Until the end of that player's next turn, they may play that card.
[0]: Gain control of target creature or planeswalker until end of turn. Tap it.
[–9]: Take an extra turn after this one. During that turn, you control all opponents.