msem-instigator

You may sacrifice three artifacts rather than pay this spell's mana cost.
Exile three artifact cards from your graveyard: Return Salvage Titan from your graveyard to your hand.

Whenever you gain life, target opponent loses that much life.

Target creature gets -3/-3 until end of turn. You gain 3 life.

Flying, lifelink
Whenever you gain life, you may have target creature get -X/-X until end of turn, where X is the amount of life you gained.

Flash (You may cast this spell any time you could cast an instant.)
When Sanguine Muralist enters, you may have target creature's toughness become 1 until end of turn.

Sanguine Oracle enters tapped.
{4}{B}, {T}, Sacrifice Sanguine Oracle: Target player discards two cards. Activate only as a sorcery.

{2}{B}: Return Sanitarium Skeleton from your graveyard to your hand.

Poisonous 5 (Whenever this creature deals combat damage to a player, that player gets five poison counters.)
At the beginning of your upkeep, if an opponent is poisoned, you may destroy target Human.

Poisonous 2 (Whenever this creature deals combat damage to a player, that player gets two poison counters.)
When Sankataar Scourge dies, if it attacked this turn, target opponent gets a poison counter.

{B}, Pay 1 life: Target creature's controller sacrifices it unless that player pays 1 life.
{B}, Sacrifice a creature: You gain life equal to the sacrificed creature's power.

When Sasori Nightrunner enters, create a 2/2 colorless Spirit creature token.
Whenever a colorless creature you control dies, each opponent loses 1 life.

Flying
Tap three untapped Satrapies you control: You may cast target card from your graveyard. Pay life equal to its mana value rather than pay its mana cost. If that spell would be put into a graveyard, exile it instead.

Deathtouch
Whenever Scaleblight Bokor attacks, it gets +1/+1 until end of turn for each Curse attached to defending player.

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

When Scaleblight Warrior enters, you gain 2 life.
Pay 2 life: Scaleblight Warrior gains menace until end of turn.

Deathtouch
Inspired — Whenever Scar Tattooist becomes untapped, you may have target creature get -1/-1 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.

At the beginning of your end step, each opponent loses 1 life for each permanent they own that you control.

Harness (You may tap a creature you control as you cast this spell. If you do, reduce this spell's mana cost by that creature's power.)
Target creature gets -X/-X until end of turn.

Target player reveals their hand. You choose a nonland card from it. That player discards that card. 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.”)

Whenever another creature dies, you gain 1 life.

As Scavenging Sandwurm enters, choose decay or remain.
When Scavenging Sandwurm dies,
• Decay — Draw a card.
• Remain — Create a 2/2 black Zombie creature token.

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.”)

Scion of Belmord has lifelink as long as it's embattled. (A creature is embattled if it has a counter on it or a permanent you control attached to it.)

Deathtouch
When Scion of Desolation enters, put target creature card with mana value 3 or less from a graveyard onto the battlefield under your control.
Whenever a Swamp you control enters, you may aetherize Scion of Desolation. (To aetherize, create a token that's a copy of it, then exile that token.)