Storm Crow

Creature — Bird (1/2)

Flying (This creature can't be blocked except by creatures with flying or reach.)

Stormchaser Drake

Creature — Drake (2/1)

Flying
Whenever Stormchaser Drake becomes the target of a spell you control, draw a card.

Stormkeld Prowler

Creature — Human Rogue (2/1)

Whenever you cast a spell with mana value 5 or greater, put two +1/+1 counters on Stormkeld Prowler.

Stormscape Familiar

Creature — Bird (1/1)

Flying
White spells and black spells you cast cost less to cast.

Stratus Dancer

Creature — Djinn Monk (2/1)

Flying
Megamorph (You may cast this card face down as a 2/2 creature for . Turn it face up any time for its megamorph cost and put a +1/+1 counter on it.)
When Stratus Dancer is turned face up, counter target instant or sorcery spell.

Straw Soldiers

Creature — Scarecrow Soldier (1/3)

Supreme Phantom

Creature — Spirit (1/3)

Flying
Other Spirits you control get +1/+1.

Surge Mare

Creature — Horse Fish (0/5)

Surge Mare can't be blocked by green creatures.
Whenever Surge Mare deals damage to an opponent, you may draw a card. If you do, discard a card.
: Surge Mare gets +2/-2 until end of turn.

Surveilling Sprite

Creature — Faerie Rogue (1/1)

Flying
When Surveilling Sprite dies, you may draw a card.

Suspicious Stowaway // Seafaring Werewolf

Creature — Human Rogue Werewolf // Creature — Werewolf (1/1)

Suspicious Stowaway can't be blocked.
Whenever Suspicious Stowaway deals combat damage to a player, draw a card, then discard a card.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Seafaring Werewolf

Seafaring Werewolf can't be blocked.
Whenever Seafaring Werewolf deals combat damage to a player, draw a card.
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Svyelunite Priest

Creature — Merfolk Cleric (1/1)

, : Target creature gains shroud until end of turn. Activate only during your upkeep. (It can't be the target of spells or abilities.)

Sworn Guardian

Creature — Merfolk Warrior (1/3)

Tah-Crop Skirmisher

Creature — Naga Warrior (2/1)

Embalm (, Exile this card from your graveyard: Create a token that's a copy of it, except it's a white Zombie Naga Warrior with no mana cost. Embalm only as a sorcery.)

Talas Merchant

Creature — Human Pirate (1/3)

Talas Scout

Creature — Human Pirate Scout (1/2)

Flying

Tattered Haunter

Creature — Spirit (2/1)

Flying
Tattered Haunter can block only creatures with flying.

Tawnos, Solemn Survivor

Legendary Creature — Human Artificer (1/3)

, : Create a token that's a copy of up to one target artifact token you control. Mill two cards.
, , Sacrifice two artifact tokens, Exile an artifact or creature card from your graveyard: Create a token that's a copy of the exiled card, except it's an artifact in addition to its other types. Activate only as a sorcery.

Tetsuko Umezawa, Fugitive

Legendary Creature — Human Rogue (1/3)

Creatures you control with power or toughness 1 or less can't be blocked.

Thalakos Sentry

Creature — Thalakos Soldier (1/2)

Shadow (This creature can block or be blocked by only creatures with shadow.)

The Reality Chip

Legendary Artifact Creature — Equipment Jellyfish (0/4)

You may look at the top card of your library any time.
As long as The Reality Chip is attached to a creature, you may play lands and cast spells from the top of your library.
Reconfigure (: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)