msem-instigator

Whenever another creature you control enters, target opponent loses 1 life and you gain 1 life.
Sacrifice Somber River Bearer: Creatures you control gain indestructible until end of turn.

Improve {1} ({1}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
At the beginning of your end step, exile up to one target nonland permanent you own. If Soul Reader has two or more counters on it, return that card to the battlefield under your control. Otherwise, return that card to your hand.

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.

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.

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.

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.)

First strike
When Soulstone Commander enters, return target Soldier creature card from your graveyard to the battlefield. That creature is a Spirit in addition to its other types.

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.

Whenever a land you control enters, you gain 1 life.
{3}{G}, Sacrifice Sower of Spring: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Flying
When Spawn of Keranos enters, you may draw a card. If you do, discard a card unless you control another creature with flying.

Each creature you control that has been dealt damage this turn by a source you controlled has indestructible.

Haste
When Speaker of the Iris enters, abound. (To abound, you may cast a spell that costs less than this from your hand without paying its mana cost.)
Other creatures you control have haste.

When Specialist Saboteur enters, choose one —
• Put a +1/+1 counter on Specialist
Saboteur.
• Destroy target enchantment.

Whenever you cast a noncreature spell, create a 1/1 colorless Servo artifact creature token.
{1}{U}, {T}, Exile three noncreature cards from your graveyard: Draw a card.

When Specimen Collector enters, you may salvage a creature card. (Exile one from your graveyard until this creature leaves the battlefield. Whenever this creature deals combat damage to a player, put a card it salvaged into your hand.)

When Spectral Kitsune enters, you may remove a counter from target player or permanent.

Flying
When Spectre of Terror deals combat damage to a player, that player discards a card.
Madness {1}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Spirited (When this creature enters, you may activate one of its activated abilities without paying its cost.)
{2}{R}{R}: If an instant or sorcery source you control would deal damage to a permanent or player this turn, it deals that much damage plus 2 instead.

Haste
Whenever Spellmaw Crocodile deals combat damage to a player, draw a card.
Discard a card: Spellmaw Crocodile can't be blocked this turn.

Haste
Whenever Spellslinger Elf deals combat damage to a player, draw a card, then you may cast a card from your hand with mana value 3 or less without paying its mana cost.

When Spiked Burrower dies, if it didn't have a counter on it, return it to the battlefield under your control with a +1/+1 counter or a lifelink counter on it.

Flash
If an opponent would gain life or damage to a permanent or opponent would be prevented, instead Spirit-Lantern Incendiary deals 1 damage to that permanent or opponent.

Vigilance, reach
{T}: Splitshaft Deadeye deals damage equal to its power to target creature with flying.