msem-instigator

When Serene Initiate enters, rouse 1. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)
{3}{G}{G}: Creatures you control get +2/+2 and gain trample until end of turn.

Equipped creature gets +1/+1 and has deathtouch.
{1}: Serpent Staff becomes a 1/1 green Snake creature with deathtouch and loses all other abilities until end of turn.
Equip {3}

Enchant creature
Enchanted creature can't attack.
Civilized — Enchanted creature can't block and its activated abilities can't be activated if you control an artifact, a creature, and an enchantment.

{2}: Settlement Guardian gets +1/+1 until end of turn for each color of mana spent to activate this ability.

Search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Amass Soldiers 1. (Put a +1/+1 counter on an Army you control. It's also a Soldier. If you don't control one, create an 0/0 black Soldier Army creature token first.)

Destroy target token.

Vigilance
Sha'Iv's Emissary gets +1/+1 as long as you control a blue or red permanent.

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

Shadow Courier can't be blocked.

Your opponents play with their hands revealed.

When Shadow of Izumito dies, choose one —
• Destroy target creature that was dealt damage this turn.
• You may put a progress counter on a Project you control.

Shadowband Consul enters tapped.
{B}, Pay 2 life: Return Shadowband Consul from your graveyard to the battlefield. Activate only if an opponent lost life this turn.

Sacrifice Shadowfeeder: Target player loses 1 life and you gain 1 life.

Prowess
Each instant and sorcery card with mana value 3 or less in your hand has inscribe. The inscribe cost is equal to its mana cost increased by {1}{U/R}. (Pay that card's mana cost increased by {1}{U/R}: Exile that card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)

When Shaidostan Cryoforger enters, exile the top card of your library.
When Shaidostan Cryoforger dies, you may put the exiled card into your hand.

As long as Shambling Morass is on the battlefield or in your graveyard, it's a land in addition to its other types.
When Shambling Morass dies, you may pay {1}. If you do, you draw a card and you lose 1 life.

Create a colorless Equipment artifact token with “Equipped creature gets +1/+1” and equip {1}. You may attach it to a creature you control.
Inscribe {3}{R} ({3}{R}: Exile this card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)

Frenzy 2 (Whenever this creature attacks and isn't blocked, it gets +2/+0 until end of turn.)

Discard a card, then draw a card.
Compose (Then if you cast this from your hand, exile it and create a Saga token with “r3—You may cast a copy of this card from exile without paying its mana cost.”)

Create a 1/1 colorless Human creature token. Put your choice of a flying, vigilance, prowess, or hexproof counter on it. If you control a permanent with mana value 5 or greater, instead put any number of those counters and a +1/+1 counter on it.

As long as it's your turn, Shell Merc has first strike and prowess.

Concord — {T}: Tap target nonland permanent. Activate only if there are four or more card types among permanents you control.

You may look at the top card of your library any time.
{T}: Target player mills a card.

Shepherd of the People can't be blocked by creatures with power 2 or less.
Whenever another Citizen or Peasant you control enters, Shepherd of the People gets +1/+1 until end of turn.

Art of war — At the beginning of your end step, if Sheraku Elite dealt damage to an opponent this turn, put a +1/+1 counter on it.