Shield of the Realm

If a source would deal damage to equipped creature, prevent 2 of that damage.
Equip {1}

Shieldmage Advocate

{T}: Return target card from an opponent's graveyard to their hand. Prevent all damage that would be dealt to any target this turn by a source of your choice.

Seasoned Tactician

{3}, Exile the top four cards of your library: The next time a source of your choice would deal damage to you this turn, prevent that damage.

Serra Paladin

{T}: Prevent the next 1 damage that would be dealt to any target this turn.
{1}{W}{W}, {T}: Target creature gains vigilance until end of turn.

Shieldmage Elder

Tap two untapped Clerics you control: Prevent all damage target creature would deal this turn.
Tap two untapped Wizards you control: Prevent all damage target spell would deal this turn.

Kami of False Hope

Sacrifice this creature: Prevent all combat damage that would be dealt this turn.

Shieldmate's Blessing

Prevent the next 3 damage that would be dealt to any target this turn.

Selfless Squire

Flash
When this creature enters, prevent all damage that would be dealt to you this turn.
Whenever damage that would be dealt to you is prevented, put that many +1/+1 counters on this creature.

Losheel, Clockwork Scholar

Prevent all combat damage that would be dealt to attacking artifact creatures you control.
Whenever one or more artifact creatures you control enter, draw a card. This ability triggers only once each turn.

Shield of the Ages

{2}: Prevent the next 1 damage that would be dealt to you this turn.

Serra's Hymn

At the beginning of your upkeep, you may put a verse counter on this enchantment.
Sacrifice this enchantment: Prevent the next X damage that would be dealt this turn to any number of targets, divided as you choose, where X is the number of verse counters on this enchantment.

Shield of the Avatar

If a source would deal damage to equipped creature, prevent X of that damage, where X is the number of creatures you control.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Seraph of the Sword

Flying
Prevent all combat damage that would be dealt to this creature.

Silhouette

Choose target creature. If a spell or ability that targets that creature would cause a source to deal damage to that creature this turn, prevent that damage.

Soldevi Heretic

{W}, {T}: Prevent the next 2 damage that would be dealt to target creature this turn. Target opponent may draw a card.

Shielded Passage

Prevent all damage that would be dealt to target creature this turn.

Sivvi's Ruse

If an opponent controls a Mountain and you control a Plains, you may cast this spell without paying its mana cost.
Prevent all damage that would be dealt this turn to creatures you control.

Holy Day

Prevent all combat damage that would be dealt this turn.

Scars of the Veteran

You may exile a white card from your hand rather than pay this spell's mana cost.
Prevent the next 7 damage that would be dealt to any target this turn. If it's a creature, put a +0/+1 counter on it for each 1 damage prevented this way at the beginning of the next end step.

Shadowbane

The next time a source of your choice would deal damage to you and/or creatures you control this turn, prevent that damage. If damage from a black source is prevented this way, you gain that much life.

Songstitcher

{1}{W}: Prevent all combat damage that would be dealt this turn by target attacking creature with flying.

Divine Deflection

Prevent the next X damage that would be dealt to you and/or permanents you control this turn. If damage is prevented this way, Divine Deflection deals that much damage to any target.

Scarecrow

{6}, {T}: Prevent all damage that would be dealt to you this turn by creatures with flying.

Security Blockade

Enchant land
When this Aura enters, create a 2/2 white Knight creature token with vigilance.
Enchanted land has "{T}: Prevent the next 1 damage that would be dealt to you this turn."

Solitary Confinement

At the beginning of your upkeep, sacrifice this enchantment 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.