msem-instigator

Whenever Shifty Fink attacks, if you have more cards in hand than defending player, it gets +2/+1 until end of turn.

When Shifty Squirrel enters, you gain 3 life.
Sacrifice a creature: Transform Shifty Squirrel.

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.

Equipped creature gets +2/+2.
Art of war — At the beginning of your end step, if equipped creature dealt damage to an opponent this turn, draw a card.
Equip {2}

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, up to three target permanents become colorless Island lands.

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

Shikai Revenant enters tapped.
At the beginning of your end step, if an opponent lost life this turn, you may return Shikai Revenant from your graveyard to your hand.

{T}: Add {C}.
Discard Shikai's Redoubt: Exile up to two target cards from graveyards.

Equipped creature has haste.
At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary if equipped creature is legendary. That token gains haste. Exile it at the beginning of the next end step.
Equip {2}

Enchant creature
Enchanted creature has lifelink and protection from its colors. This effect doesn't remove Shimmerhold. (This permanent can't be targeted, dealt damage, enchanted, or equipped by anything its color.)

Flying, haste
Whenever Shimmering Dragon attacks, for each creature you control, create a tapped and attacking token that's a copy of that creature. Exile the tokens at the beginning of the end step.

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

Whenever you scry, put a +1/+1 counter on Shimmershell.

Whenever equipped creature attacks, put a charge counter on Shimmersting, then create a token that's a copy of equipped creature and that's tapped and attacking for each charge counter on Shimmersting, except the tokens aren't legendary. Exile the tokens at the beginning of the end step.
Equip {5}

Whenever Shina Taiyohata or another creature you control enters, you may have that creature gain haste. If you do, return that creature from the battlefield to its owner's hand at the beginning of the next end step.

[+2]: Exile any number of target artifacts and/or enchantments you control, then return them to the battlefield under your control. You may draw that many cards.
[–4]: Search your library for an enchantment card, put that card onto the battlefield, then shuffle.
[–12]: Put any number of permanent cards you own from outside the game onto the battlefield tapped.

Shining Crusader has protection from all colors as long as you control no colored permanents.

When you unveil Shining Elementalist, creatures can't block this turn.

Deception {U}{B} ({U}{B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Sacrifice a creature: Shinrei of the Ghosting Way can't be blocked this turn.
Whenever one or more Rogues you control deal combat damage to a player, return a creature card from your graveyard to your hand.

Flash
If one or more counters would be put on a creature you control, put that many plus one of each of those kinds of counters on that creature instead.

{T}: Add one mana of any color. Activate only if Shinrin Sage is enchanted, equipped, or has a card inscribed onto it.

Flash
When Shinrin Spellhunter enters, if an opponent cast a noncreature spell this turn, draw a card.

Flying, lifelink
Whenever Shioki, Imperial Heir attacks, exile any number of other target nonland permanents you control, then return those cards to the battlefield under their owner's control.

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.