msem-instigator

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Whenever a creature you control attacks alone this turn, put a +1/+1 counter on it.
III — Whenever a creature you control attacks alone this turn, it gains double strike and lifelink until end of turn.

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

Enchant creature
When Shadow Infestation enters the battlefield, enchanted creature's controller loses 2 life.
Enchanted creature gets -1/-1 and can't block.

Flash
When Shadow Stalker enters the battlefield, for each player, look at the top card of that player's library. You may have that player put that card into their graveyard.

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

When Shambling Gutless enters the battlefield, target player discards a card.

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you cast a noncreature spell, 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.”)

Creatures you control get +1/+0.
Ferocious — At the beginning of combat on your turn, creatures you control with power 4 or greater gain trample until end of turn.

When Shawlbinder enters the battlefield, if you control a Desert, exile another target permanent. Return that card to the battlefield under its owner's control at the beginning of the next end step.

Equipped creature gets +1/+2 and has vigilance.
Equip {3}

When Sheltered Diviner enters the battlefield, each player mills three cards.

Whenever a creature you control dies, 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 you sacrifice a noncreature permanent, each opponent loses 1 life and you gain 1 life.

Flash
This spell can't be countered.
Whenever Shigurei attacks, you may activate an ability of a creature you control without paying its cost.
{1}{G}{U}: Target permanent becomes a colorless Island land until end of turn.

Trample
When Shigurei, the Floodbringer enters the battlefield, up to three target permanents become colorless Island lands.

Shimmering Seadragon gets +1/+0 and can't be blocked as long as you control a legendary creature.

Create a token that's a copy of target creature.
Metamorph {2}{U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up and cast it at any time for its metamorph cost.)

Enchant creature you control
At the beginning of your upkeep, create a token that's a copy of enchanted creature.

{8}{U}{U}: Monstrosity 5. (If this creature isn't monstrous, put five +1/+1 counters on it and it becomes monstrous.)
When Shipway Whale becomes monstrous, target player exiles all cards in their library, then shuffles their graveyard into their library.

This spell has flash as long as an opponent is cursed.
Return target creature to its owner's hand.
Draw a card.

Flying
When Shoal Raker enters the battlefield, draw a card if an opponent is cursed.

Shock Blast deals X damage to target creature, where X is the number of instant and sorcery cards in your graveyard.

When Shojiro, the Wavewaker enters the battlefield, submerge up to eight target creatures your opponents control. (To submerge a card, exile it, then put it on the battlefield face down under its owner's control as a 2/2 creature.)

{3}{U}{U}: Monstrosity 4. (If this creature isn't monstrous, put four +1/+1 counters on it and it becomes monstrous.)
When Shorecrash Octopus becomes monstrous, return target instant or sorcery card from your graveyard to your hand.

Equipped creature gets +1/+1.
Equip {1}

{2/W}{2/W}: Shrapnel Golem deals 3 damage to target creature blocking it.