Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

Sun Titan

Vigilance
Whenever Sun Titan enters or attacks, you may return target permanent card with mana value 3 or less from your graveyard to the battlefield.

Cleric Class

(Gain the next level as a sorcery to add its ability.)
If you would gain life, you gain that much life plus 1 instead.
{3}{W}: Level 2
Whenever you gain life, put a +1/+1 counter on target creature you control.
{4}{W}: Level 3
When this Class becomes level 3, return target creature card from your graveyard to the battlefield. You gain life equal to that creature's toughness.

Linden, the Steadfast Queen

Vigilance
Whenever a white creature you control attacks, you gain 1 life.

Tonic Peddler

{W}, {T}, Discard a card: Target player gains 3 life.

Solitary Confinement

At the beginning of your upkeep, sacrifice Solitary Confinement unless you discard a card.
Skip your draw step.
You have shroud. (You can't be the target of spells or abilities.)
Prevent all damage that would be dealt to you.

The Underworld Cookbook

{T}, Discard a card: Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")
{4}, {T}, Sacrifice The Underworld Cookbook: Return target creature card from your graveyard to your hand.

Solemn Simulacrum

When Solemn Simulacrum enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When Solemn Simulacrum dies, you may draw a card.

Thraben Standard Bearer

{1}{W}, {T}, Discard a card: Create a 1/1 white Human Soldier creature token.

Sol Ring

Vengeful Dreams

As an additional cost to cast this spell, discard X cards.
Exile X target attacking creatures.

Sliversmith

{1}, {T}, Discard a card: Create a 1/1 colorless Sliver artifact creature token named Metallic Sliver.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Trading Post

{1}, {T}, Discard a card: You gain 4 life.
{1}, {T}, Pay 1 life: Create a 0/1 white Goat creature token.
{1}, {T}, Sacrifice a creature: Return target artifact card from your graveyard to your hand.
{1}, {T}, Sacrifice an artifact: Draw a card.