msem-instigator

Equipped creature gets +2/+2 and has flying and lifelink.
When equipped creature deals combat damage to a player, unattach Shionoshio, Ocean's Vow, then transform it.
Equip {W}{U}
Shionoshio can be your commander.

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.

Whenever you cast a noncreature spell, Shiverpass Taskmage explores. (Reveal the top card of your library. Put it into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then you may put that card in your graveyard.)

When Shizen, the Thousand Steps enters, draw a card, then choose a creature card name.
Creatures you control with the chosen name get +0/+1 and have hexproof.

Partner with Kasoha, Keeper of Truths (When this creature enters, target player may put Kasoha into their hand from their library, then shuffle.)
Whenever Shizura, Keeper of Traditions or another legendary creature dies, target player draws two cards and loses 2 life.

Flying
Instant and sorcery spells you cast cost {1} less to cast.
Whenever you cast your second spell each turn, draw a card.

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

Spells your opponents cast that target Shoalshine cost an additional {2} to cast.
Concord — {T}: Draw a card. Activate only if there are four or more card types among permanents you control.

Shock deals 2 damage to any target.

Equipped creature gets +2/+0.
Equipped creature has first strike as long as it's attacking.
Equip {2}

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

Shock and Awe deals 2 damage to target creature. Creatures can't block this turn.

Reveal the top four cards of your library and separate them into two piles. An opponent chooses one of those piles. Put that pile into your hand. Shuffle the other and up to four cards from your graveyard into your library.

Vanguard — Whenever a creature you control attacks alone, Shocking Ewe deals 2 damage to defending player.

When Shojiro, the Wavewaker enters, 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.)

Shokan Battalion has double strike as long as it's enchanted, equipped, or has a card inscribed onto it.

When Shokan Captain enters, you may search your library for an Equipment card, reveal it, shuffle, then put that card on top.
Art of war — At the beginning of your end step, if Shokan Captain dealt damage to an opponent this turn, put a +1/+1 counter on it.

Target creature gains hexproof until end of turn.
Monument {2}{U} (You may cast this transformed from your graveyard for its monument cost. Exile it if it would leave the battlefield or not resolve.)

Flying
When Shomi's Savior enters, scry 3, then you gain 3 life.
Whenever you scry, put a +1/+1 counter on Shomi's Savior.

Target creature you control deals damage equal to its power to target creature with flying.

{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.

Whenever Shoreline Stormers deals damage to a player, draw a card.
{2}{U}: Target creature can't be blocked this turn.

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Marked creatures your opponents control lose all abilities.