msem-instigator

{T}: Add {C}.
{2}, Pay 2 life: Starved Oasis becomes a 4/2 Elemental creature until end of turn. It's still a land.

Until end of turn, if a source you don't control would deal damage to you or cause you to lose life, mill that many cards instead.

Target opponent discards a card at random. If that card's mana value is 3 or less, you may cast it without paying its mana cost.

Enchant creature
When Sticky Fingers enters, draw a card.
Enchanted creature gets +2/+0 and can't be blocked.

Counter target noncreature spell. Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

When Still-Smoke Skirmisher dies, each opponent loses 1 life and you gain 1 life. Then return Still-Smoke Skirmisher to the battlefield at the beginning of the next end step if it was sacrificed.

Creature cards in your graveyard have revive. The revive cost is equal to their mana cost. (Pay that creature's mana cost, Exile that card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Stinging Swordfish has first strike as long as it's attacking.
When Stinging Swordfish dies, create an Equipment enchantment artifact token named Fish Sword with “Equipped creature gets +3/+1,” “Equipped creature has first strike as long as it's attacking,” and equip {2}. You may attach that token to a creature you control.

When Stoic Observation enters, mill two cards, then you may return a creature card from your graveyard to your hand.
{3}{G}, Exile a creature card from your graveyard: Create a 2/2 green Wolf creature token. You gain 2 life.

Choose a nonland card type. Target player reveals their hand. You choose a card of the chosen type from it. That player discards that card.

When Stonefall Golem leaves the battlefield, destroy target permanent.

At the beginning of your upkeep, if Stonework Infantry is on the battlefield, each player returns all cards named Stonework Infantry from their graveyard to the battlefield.

{T}: Add {C}.
{T}, Exile two cards from your graveyard: Add {U} or {R}.

Flying
Stormcloud Drake gets +1/+0 for each instant and sorcery card in your graveyard.
Whenever Stormcloud Drake attacks, tap target creature defending player controls.

Prowess, haste

Stormsurge deals 3 damage to any target.
Orchestrate {R} (You may exile this card from your hand anytime you could cast a sorcery for its orchestrate cost. When you next resolve a spell, you may cast this from exile without paying its mana cost.)

Draw a card. Then you may cast an instant spell with mana value 2 or less from your hand without paying its mana cost.

Flying
Prophecy {0} (Once each turn, you may exile a card with prophecy as you reveal it. When you do, you may cast it for its prophecy cost as long as it's exiled.)

If you would lose the game, instead sacrifice a storied permanent. If you do and your life total is less than 1, it becomes 1.

At the beginning of your upkeep, mill two cards.
{1}{G}, Sacrifice Strange Discovery: Return target card from your graveyard to your hand.

Target creature gets -2/-2 until end of turn. If you control two or more Deserts, destroy that creature instead.

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.

When Strayseeker Ranger enters, search your library for a creature card with mana value 2 or less, reveal it, put it into your hand, then shuffle.
Recite {W}{W} (You may cast this creature from your graveyard for its recite cost. If you do, exile it when it enters or if it would leave the battlefield.)

When Street Performer enters, create a 2/1 blue Illusion creature token with “When this creature becomes the target of a spell or ability, sacrifice it.”

Strident Retainer's power and toughness are each equal to the number of creatures you control.
Art of war — At the beginning of your end step, if Strident Retainer dealt damage to an opponent this turn, create a 1/1 colorless Samurai creature token.