msem-instigator

{2}{G}: Look at the top three cards of your library. You may reveal a creature or Revelation card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

When Stillmarsh Brinecatcher enters, return another target nonland permanent to its owner's hand.
At the beginning of your end step, if you control a permanent with mana value 5 or greater, you may sacrifice Stillmarsh Brinecatcher. If you do, draw a card and create a 3/2 colorless Horror creature token.

When Stilthorpe Falconer enters, create a 1/1 white Bird creature token with flying.

Whenever this creature or another Citizen or Peasant you control enters, you may exile target card from a graveyard. If you exile a creature card this way, you gain 1 life.

Flying
Whenever Stingsower attacks, you may pay {3}{B}{B}. If you do, target creature gets -1/-1 for each Insect you control until end of turn.

Flying
Whenever you cast your first spell each turn, add {U}{U}, {U}{R}, or {R}{R}.
Whenever you cast your second spell each turn, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Whenever you cast your third spell each turn, Stirring Igmel deals 3 damage to each opponent.

Stoic Djinn has flying as long as it has a counter on it.

Improve {1} ({1}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
{3}{W}: Return target nonland permanent card with mana value 1 or less from your graveyard to your hand. This ability cost {1} less to activate for each counter on Stoneport Provisioner.

Stormbred Elemental gets +1/+1 as long as you control an Island.
{U}: Stormbred Elemental gains flying until end of turn.

Other artifacts you control have ward {1}.
Overcast — Whenever you cast an artifact creature spell, if {C} was spent to cast it, it enters with an additional +1/+1 counter on it.

Vigilance
{4}{U}: Draw a card.

At the beginning of your upkeep, you may pay 2 life. If you do, exile the top card of target opponent's library. If a nonland card is exiled this way, copy it. You may cast the copy. (You still pay its costs, including color. Copies of permanents enter as tokens.)

Prowess
Pay 2 life: Change a target of target spell or ability to Straw Intellectual.

As Straw Simulacrum enters, choose a creature type.
Straw Simulacrum is the chosen creature type in addition to its other types.
Other creatures you control of the chosen type get +1/+1.

Whenever another creature you control enters, put your choice of a +1/+1 counter, a trample counter, or a haste counter on it.

Stray Sighthound can't be blocked by creatures with power 2 or less.
Attain {3}{G} ({3}{G}: Transform this. Spend at least three colors of mana to activate this, and only as a sorcery.)

Wither (This deals damage to creatures in the form of -1/-1 counters.)

Menace
Deploy 4 (As this enters, you may tap any number of other creatures you control with total power 4 or more.)
When Street Raider enters deployed, discard your hand, then draw three cards.

Ward {1}
Streetslipper can't be blocked.
Whenever you foretell a card or cast a foretold spell, put a +1/+1 counter on Streetslipper.

When Strength of the Patient enters, if it was revived, put four +1/+1 counters on it.
Revive {4}{W}{W}{W} ({4}{W}{W}{W}, 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.)

You may have Strikebreaker enter as a copy of a non-Aura enchantment you control, except it's a 2/2 Construct Actor creature in addition to its types.

Whenever you cast an instant, sorcery, or Curse spell, Stromkirk Sangromancer deals 1 damage to each opponent.

Whenever another Warrior creature you control attacks, you may return Stubborn Blademate from your graveyard to the battlefield tapped and attacking. If you do, sacrifice it at end of combat.

Prowess
Art of war — At the beginning of your end step, if Student of Shigure dealt damage to an opponent this turn, you may draw a card, then discard a card.

When Student of the Crane enters, create a 1/1 white Bird creature token with flying.