msem-instigator

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

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.)
When Soul Trapper enters, tap target creature an opponent controls. That creature doesn't untap during its controller's untap step for as long as you control Soul Trapper.

Whenever another creature enters, you gain 1 life.

Soul of Misery gets +1/+1 as long as you control a Swamp.
{4}{B}: Target player discards a card. Activate only as a sorcery.

When Soul of the Sands enters, choose one —
• You gain 4 life.
• If you gained life this turn, draw a card.

Whenever another creature enters, you may gain 1 life.

{1}, {T}, Sacrifice Soul-Synthesizer: Look at the top seven cards of your library. You may reveal a card with an activated ability from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Advance {2}{R} (Cast this for {2}{R} to advance it as it enters. {2}{R}: Advance this as a sorcery.)
Haste
Whenever Soulblade Warrior advances, it gets +2/+0 until end of turn.

{1}, Sacrifice a creature: Each opponent loses 1 life and you gain 1 life.

Other Spirits you control get +1/+1.
As long as a Spirit you control has flying, Soulcleaver has flying. The same is true for first strike, double strike, deathtouch, haste, hexproof, indestructible, lifelink, menace, reach, trample, and vigilance.

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.)
Haste

At the beginning of each end step, if you gained life this turn, put a +1/+1 counter on a creature you control.

Flash
Other Rogues you control get +1/+1.
Rogue spells you cast have flash.

Destroy target creature. Then if you control a Wizard, that creature's controller loses 1 life for each creature card in their graveyard.

Flying
Whenever Souls of the Jury enters or an opponent fails a trial, create a 1/1 white Cleric creature token.

Soulsmoke Adept gets +1/+0 and has lifelink as long as it's embattled. (A creature is embattled if it has a counter on it or has a permanent you control attached to it.)

Sacrifice a creature: Soulsorrow Shade gets +2/+2 until end of turn.

Bulwark — Whenever Soulstone Servant attacks, if you control a creature with toughness 4 or greater, Soulstone Servant gets +2/+2 and gains flying until end of turn.

{3}, {T}, Sacrifice a non-Spirit creature: Create a 1/1 white Spirit creature token with flying.

If target creature would leave the battlefield this turn, return it to its owner's hand instead.
Fuse (You may cast one or both halves of this card from your hand.)

Create a 1/1 blue Advisor creature token.
Draw a card.

Put a +1/+1 counter on each creature you control. (Then exile this card. You may cast the creature later from exile.)

Source Decay deals 2 damage to each opponent. Create two 1/1 colorless Servo artifact creature tokens.
Whenever a creature you control deals combat damage to a player, you may pay {2}{B}{R} and sacrifice it. If you do, return Source Decay from your graveyard to your hand.

{1}, Sacrifice Sovereign Stone: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
{1}, Sacrifice Sovereign Stone: Draw a card.

Counter target spell unless its controller pays {X}. Look at the top X cards of your library. Put up to one of them on top of your library and the rest on the bottom of your library in a random order.