Scion of Vitu-Ghazi

When this creature enters, if you cast it from your hand, create a 1/1 white Bird creature token with flying, then populate. (Create a token that's a copy of a creature token you control.)

Shire Shirriff

Vigilance
When this creature enters, you may sacrifice a token. When you do, exile target creature an opponent controls until this creature leaves the battlefield.

Sephara, Sky's Blade

You may pay {W} and tap four untapped creatures you control with flying rather than pay this spell's mana cost.
Flying, lifelink
Other creatures you control with flying have indestructible. (Damage and effects that say "destroy" don't destroy them.)

Star Compass

This artifact enters tapped.
{T}: Add one mana of any color that a basic land you control could produce.

Securitron Squadron

Squad {3} (As an additional cost to cast this spell, you may pay {3} any number of times. When this creature enters, create that many tokens that are copies of it.)
Vigilance
Whenever a creature token you control enters, put a +1/+1 counter on it.

Symmetry Matrix

Whenever a creature you control with power equal to its toughness enters, you may pay {1}. If you do, draw a card.

Serra Redeemer

Flying
Whenever another creature you control with power 2 or less enters, put two +1/+1 counters on that creature.

Springleaf Drum

{T}, Tap an untapped creature you control: Add one mana of any color.

Scholar of New Horizons

This creature enters with a +1/+1 counter on it.
{T}, Remove a counter from a permanent you control: Search your library for a Plains card and reveal it. If an opponent controls more lands than you, you may put that card onto the battlefield tapped. If you don't put the card onto the battlefield, put it into your hand. Then shuffle.

Sisay's Ring

Stonespeaker Crystal

{T}: Add {C}{C}.
{2}, {T}, Sacrifice this artifact: Exile any number of target players' graveyards. Draw a card.

Staff of the Storyteller

When this artifact enters, create a 1/1 white Spirit creature token with flying.
Whenever you create one or more creature tokens, put a story counter on this artifact.
{W}, {T}, Remove a story counter from this artifact: Draw a card.

Radiant, Serra Archangel

Flying
Tap another untapped creature you control with flying: Radiant gains protection from the color of your choice until end of turn.
Partner (You can have two commanders if both have partner.)

Sol Talisman

Suspend 3—{1} (Rather than cast this card from your hand, pay {1} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
{T}: Add {C}{C}.

Sol Ring

Sanctifier of Souls

Whenever another creature you control enters, this creature gets +1/+1 until end of turn.
{2}{W}, Exile a creature card from your graveyard: Create a 1/1 white Spirit creature token with flying.

Katerina of Myra's Marvels

As Katerina of Myra's Marvels enters, choose a letter.
Whenever you cast a spell whose name begins with the chosen letter, create a white 2/2 Cat creature token with flying.
Partner (You can have two commanders if they both have partner.)