msem-instigator

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
Whenever you casting a noncreature spell causes an ability of a creature you control to trigger, that creature gains your choice of first strike, haste, menace, or trample until end of turn.

Advance {4}{B} (Cast this for {4}{B} to advance it as it enters. {4}{B}: Advance this as a sorcery.)
Whenever Shearing Vampire advances, target player discards a card.

Assault {2}{R}{G} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
When Shemesh assaults, other creatures you control get +2/+2 and gain trample until end of turn.

Revive—{B}, Discard a card. ({B}, Discard a card, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Whenever a land you control enters, you may tap target creature.

(Transcend as a sorcery to gain that type and a +1/+1 counter.)
Ward—Discard a card.
{B}{R}: Demigod — Draw a card, then discard a card. You may have each opponent sacrifice a nonland permanent with the same mana value as the discarded card.
{4}{B}{R}: God — Create two tokens that are copies of Shi Hou's back face.

Whenever Shianne's Guardian or another creature you control enters, you may pay {1}{R}{G}. When you do, that creature deals damage equal to its power to any target.

Archive 7 (As this enters, shuffle the top seven cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
As long as you control five or more creatures, you may play permanent cards from the archived library.

Other creatures you control get +0/+1.
Whenever a creature you control perseveres, you gain 1 life. (A creature perseveres when it survives damage.)

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

Enchant creature
Enchanted creature gets +0/+2 and can block an additional creature each combat.

Search your library for a Desert card or a land card with a basic land type and put it onto the battlefield tapped, then shuffle.

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

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}

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}

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.)

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.

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

Kicker—Return a creature you control to its owner's hand. (You may return a creature you control to its owner's hand in addition to any other costs as you cast this spell.)
Counter target spell. If Shinrei's Ruse was kicked, draw a card.

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.

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

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.

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

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