msem-instigator

Whenever equipped creature deals combat damage to a player, return to your hand all cards from your graveyard that were put there this turn.
Equip {3}

Your opponents play with their hands revealed.

Shadowcleft Hideout enters tapped.
{T}: Add {B}.
{T}, Pay 2 life, Sacrifice Shadowcleft Hideout: Draw a card.

({T}: Add {B}.)
Shadowed Slums enters tapped.
{B}, {T}, Reveal a black card from your hand: Target player loses 1 life.

{2}: Equipped creature phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)
Equipped creature can't be blocked except by Rogues and is a Rogue in addition to its other types.
Equip {1}

You may play Shanty Town from your graveyard as long as seven or more cards are in your graveyard.
Shanty Town enters tapped.
{T}: Add {W} or {B}.
Cycling {1}{W}{B} ({1}{W}{B}, Discard this card: Draw a card.)

When you cast an instant or sorcery spell, you may sacrifice Shard Flower. If you do, copy that spell. You may choose new targets for the copy.

Equipped creature gets +1/+1 and has distorted. (It can be blocked by tapped creatures but not untapped creatures.)
Equip {1}

As Shardstone Rift enters, you may pay 2 life. If you don't, Shardstone Rift enters tapped.
{T}, Sacrifice Shardstone Rift: Search your library for a Swamp or Mountain card, put it onto the battlefield, then shuffle.

{T}: Each player draws a card.

Sheltered Haven enters tapped.
{T}: Add {G} or {W}.
{2}{G}{W}, {T}, Sacrifice Sheltered Haven: Draw a card.

{T}: Add {C}.
As long as Shengin Heartland is in your graveyard, lands you control have “{T}: Add {G} or {U}.”

When Shield of the Unwavering enters, attach it to target creature you control.
Equipped creature gets +2/+2 and has vigilance.
Equip {3}

{T}: Add {C}.
{1}, {T}, Sacrifice Shifting City: Search your library for a basic land or Satrapy card, put it onto the battlefield tapped, then shuffle.

{T}: Add {C}.
{2}, {T}, Sacrifice Shifting Frontiers: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

({T}: Add {G} or {U}.)
Whenever Shifting Glade becomes tapped, you lose 1 life unless you control two or more basic lands.

{T}: Add {C}.
{T}, Sacrifice Shiftscape Canyon: Choose a basic land type other than Plains. Create a colorless land token that's a Plains and the chosen basic land type. Activate only during your upkeep.

{T}: Add {C}.
{T}, Sacrifice Shiftscape Cascade: Choose a basic land type other than Island. Create a colorless land token that's an Island and the chosen basic land type. Activate only during your upkeep.

{T}: Add {C}.
{T}, Sacrifice Shiftscape Crag: Choose a basic land type other than Mountain. Create a colorless land token that's a Mountain and the chosen basic land type. Activate only during your upkeep.

{T}: Add {C}.
{T}, Sacrifice Shiftscape Grove: Choose a basic land type other than Forest. Create a colorless land token that's a Forest and the chosen basic land type. Activate only during your upkeep.

{T}: Add {C}.
{T}, Sacrifice Shiftscape Morass: Choose a basic land type other than Swamp. Create a colorless land token that's a Swamp and the chosen basic land type. Activate only during your upkeep.

{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}

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}

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.