msem-instigator

When Pestilent Vermin enters, target opponent loses 2 life unless they discard a card.
Whenever you cast a Tale, you may return Pestilent Vermin from your graveyard to your hand.

Ward—Discard a card. (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player discards a card.)
You have “Ward—Discard a card.”

Lifelink
Whenever you gain life, each opponent loses 1 life.

When Polluted Servant enters, target opponent loses 1 life and you gain 1 life.
{2}{U}: Exile Polluted Servant, then return it to the battlefield tapped under your control.

Predatory Abomination has deathtouch and lifelink as long as you control another Horror.

Profane Emissary gets +2/+2 and has lifelink as long as you control a Demon.
If you would draw a card, you may instead search your library for a Demon card, reveal it, put it into your hand, then shuffle. You lose life equal to that card's mana value.

Deathtouch
Whenever a creature dealt damage by Rabid Rodent this turn dies, put a +1/+1 counter on Rabid Rodent.
{2}, Remove a +1/+1 counter from Rabid Rodent: Regenerate Rabid Rodent.

Sacrifice a creature: Rapacious Demon gets +1/+1 and gains flying until end of turn. Activate only as a sorcery.

When Ravenous Chupacabra enters, destroy target creature an opponent controls.

When Red Flower Assassin enters, destroy target creature.
Revive {5}{B} ({5}{B}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Rehison Soothemage has lifelink as long as you control another Elf.

When Reverence Seeker dies, you may return another target Knight card from your graveyard to your hand.

Pay 3 life: Put a +1/+1 counter on target creature.

When Rum Guzzler enters, forebode, then you lose 1 life. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

When Ruthless Conscript dies, arm up to two target creatures you control. (Create a colorless Equipment artifact token with “Equipped creature gets +1/+0” and equip {2}, then attach it to that creature.)

When Ryleth, Vengeful Shadow enters, create two 1/1 green Elf creature tokens.
Whenever you attack, you may pay {1}{B/G}. When you do, return target creature card with mana value less than or equal to the number of attacking creature tokens you control from your graveyard to the battlefield tapped and attacking.

Whenever Scaleblight Cutthroat attacks, each opponent loses life equal to its power.
{4}{B}{B}: Scaleblight Cutthroat gets +3/+3 until end of turn.

Advance {1}{B} (Cast this for {1}{B} to advance it as it enters. {1}{B}: Advance this as a sorcery.)
Whenever Scarcrawler advances, you lose life equal to its power, then put a +1/+1 counter on it.

Flash
When Scholar of Necromancy enters, if a creature died this turn, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Lifelink
When Seeker of Lost Secrets leaves the battlefield, you may pay 2 life. If you do, search your library for a card, put that card into your hand, then shuffle.

Deathtouch, menace
As long as you control another Knight creature, Ser Joffrey, Plague of Nines and other Knight creatures you control have first strike.

At the beginning of your upkeep, you lose 1 life.

When Shadowlurk enters, if a creature died this turn, put a +1/+1 counter on it.

Advance {4}{B} (Cast this for {4}{B} to advance it as it enters. {4}{B}: Advance this as a sorcery.)
Whenever Shearing Vampire advances, target player discards a card.

Partner with Kasoha, Keeper of Truths (When this creature enters, target player may put Kasoha into their hand from their library, then shuffle.)
Whenever Shizura, Keeper of Traditions or another legendary creature dies, target player draws two cards and loses 2 life.