msem-instigator

Whenever equipped creature deals damage to a creature, that creature gets -2/-2 until end of turn.
Equip {2}

Flying
Revive {5}{U} ({5}{U}, 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.)

Shrewd Sikoyo can't be blocked by creatures with power 4 or greater.
Shrewd Sikoyo gets +1/+0 as long as you have at least two more cards in hand than any opponent.

Flying, vigilance

Lifelink
Whenever an Aura becomes attached to Shrieking Gnoll, put a +1/+1 counter on Shrieking Gnoll, then target creature an opponent controls gets -1/-1 until end of turn for each +1/+1 counter on Shrieking Gnoll.

Flying
Sacrifice a creature: Shrieking Nightwing gets +1/+1 until end of turn.

Flying
Resolute — At the beginning of combat on your turn, Shrill Griffin gains vigilance until end of turn if its power is greater than its base power.

Haste
Whenever you sacrifice another permanent, put a +1/+1 counter on Shrine Razer.

Whenever you create an Idol token, put a +1/+1 counter on Shrine of Elder Lords.
{T}: Add {C}.
{3}: Put a +1/+1 counter on Shrine of Elder Lords, then you may have it become a 0/0 Elemental creature with vigilance until end of turn. It's still a land.

{T}: Add {C}.
{T}: Add one mana of any color. Activate only if you've cast a noncreature spell this turn.

{T}: Add {C}.
Shrine of the World-Shepherd's power and toughness are each equal to the number of differently named lands you control.
{3}{G}: Shrine of the World-Shepherd becomes a Beast creature in addition to its other types until end of turn.

{T}: Add {C}.
{T}: Choose a color. Add one mana of that color unless you control a permanent of that color. Spend this mana only to cast a permanent spell.

{2}{U}: Target creature can't be blocked this turn.

Colorless creatures you control get +1/+1.

If a spell or ability would cause a player to discard one or more cards, that player discards that many cards at random instead.
Whenever a player discards a card, that player loses 2 life.

Deathtouch (Any amount of damage this deals to a creature is enough to destroy it.)
Shrouded Cackler can't block.

Frozen Hinterlands enters tapped.
{T}: Add {W} or {B}.
{1}{W}{B}: Until end of turn, Shrouded Rooftops becomes a 3/3 white and black Illusion creature with with lifelink and “Whenever this creature attacks or blocks, torment yourself.” It's still a land. (To torment yourself, lose 3 life unless you discard a card or sacrifice a nonland permanent.)

{T}, Pay 1 life: Add one mana of any color. Spend this mana only to cast an instant or sorcery spell.

Enchant creature
When Shrouded Spoils enters, draw two cards.
Enchanted creature can't be blocked.

Shroudmaker's Domain enters tapped.
{T}: Add {W}.

This spell costs {2} less to cast for each face-down creature you control.
Flying

Shu Qin enters with your choice of a flying or +1/+1 counter on him.
At the beginning of your upkeep, choose a creature in Shu Qin's pack. He gains that creature's abilities until end of turn. (Two or more creatures you control with equal power are in a pack.)

({T}: Add {B} or {G}.)
Shuddering Node enters tapped.
{1}, {T}: Add {B}{B} or {G}{G}.

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Artifacts and creatures your opponents control enter tapped.

Vigilance
Shuye, Forever Watching's power and toughness are each equal to the number of noncreature permanents you don't control.