Knockout Blow

This spell costs {2} less to cast if it targets a red creature.
Knockout Blow deals 4 damage to target attacking or blocking creature and you gain 2 life.

Opal Guardian

When an opponent casts a creature spell, if Opal Guardian is an enchantment, Opal Guardian becomes a 3/4 Gargoyle creature with flying and protection from red.

Jodah's Avenger

{0}: Until end of turn, Jodah's Avenger gets -1/-1 and gains your choice of double strike, protection from red, vigilance, or shadow. (A creature with shadow can block or be blocked by only creatures with shadow.)

Mind Harness

Enchant red or green creature
Cumulative upkeep {1} (At the beginning of your upkeep, put an age counter on this permanent, then sacrifice it unless you pay its upkeep cost for each age counter on it.)
You control enchanted creature.

Shield Mare

Shield Mare can't be blocked by red creatures.
When Shield Mare enters or becomes the target of a spell or ability an opponent controls, you gain 3 life.

Suq'Ata Firewalker

Suq'Ata Firewalker can't be the target of red spells or abilities from red sources.
{T}: Suq'Ata Firewalker deals 1 damage to any target.

Douse

Sword of War and Peace

Equipped creature gets +2/+2 and has protection from red and from white.
Whenever equipped creature deals combat damage to a player, Sword of War and Peace deals damage to that player equal to the number of cards in their hand and you gain 1 life for each card in your hand.
Equip {2}

Crimson Acolyte

Protection from red
{W}: Target creature gains protection from red until end of turn.

Aven Smokeweaver

Absolute Law

Flashfreeze

Surge of Righteousness

Destroy target black or red creature that's attacking or blocking. You gain 2 life.

Kor Firewalker

Protection from red
Whenever a player casts a red spell, you may gain 1 life.

Vedalken Outlander

Cerulean Drake

Flying
Protection from red (This creature can't be blocked, targeted, dealt damage, enchanted, or equipped by anything red.)
Sacrifice Cerulean Drake: Counter target spell that targets you.

Surge of Salvation

You and permanents you control gain hexproof until end of turn. Prevent all damage that black and/or red sources would deal to creatures you control this turn.

Kithkin Zealot

When Kithkin Zealot enters, you gain 1 life for each black and/or red permanent target opponent controls.

Chill

Controlled Instincts

Enchant red or green creature
Enchanted creature doesn't untap during its controller's untap step.

Sword of Forge and Frontier

Equipped creature gets +2/+2 and has protection from red and from green.
Whenever equipped creature deals combat damage to a player, exile the top two cards of your library. You may play those cards this turn. You may play an additional land this turn.
Equip {2}

Tivadar of Thorn

First strike, protection from red
When Tivadar of Thorn enters, destroy target Goblin.

Barrenton Cragtreads

Barrenton Cragtreads can't be blocked by red creatures.

Celestial Purge

High Seas

Red creature spells and green creature spells cost {1} more to cast.

Circle of Protection: Red

{1}: The next time a red source of your choice would deal damage to you this turn, prevent that damage.

Silver Knight

Island

Burrenton Forge-Tender

Protection from red
Sacrifice Burrenton Forge-Tender: Prevent all damage a red source of your choice would deal this turn.

Lavinia of the Tenth

Protection from red
When Lavinia of the Tenth enters, detain each nonland permanent your opponents control with mana value 4 or less. (Until your next turn, those permanents can't attack or block and their activated abilities can't be activated.)

Change the Equation

Choose one —
• Counter target spell with mana value 2 or less.
• Counter target red or green spell with mana value 6 or less.

Plains

Fiendslayer Paladin

First strike (This creature deals combat damage before creatures without first strike.)
Lifelink (Damage dealt by this creature also causes you to gain that much life.)
Fiendslayer Paladin can't be the target of black or red spells your opponents control.

Honorable Scout

When Honorable Scout enters, you gain 2 life for each black and/or red creature target opponent controls.

Abbey Gargoyles

Lawbringer

{T}, Sacrifice Lawbringer: Exile target red creature.

Sword of Fire and Ice

Equipped creature gets +2/+2 and has protection from red and from blue.
Whenever equipped creature deals combat damage to a player, Sword of Fire and Ice deals 2 damage to any target and you draw a card.
Equip {2}

Essence Leak

Enchant permanent
As long as enchanted permanent is red or green, it has "At the beginning of your upkeep, sacrifice this permanent unless you pay its mana cost."

Lightwielder Paladin

First strike (This creature deals combat damage before creatures without first strike.)
Whenever Lightwielder Paladin deals combat damage to a player, you may exile target black or red permanent that player controls.

Blue Elemental Blast

Choose one —
• Counter target red spell.
• Destroy target red permanent.

Aether Gust

Choose target spell or permanent that's red or green. Its owner puts it on their choice of the top or bottom of their library.

Sanctifier en-Vec

Protection from black and from red
When Sanctifier en-Vec enters, exile all cards that are black or red from all graveyards.
If a black or red permanent, spell, or card not on the battlefield would be put into a graveyard, exile it instead.

Luminesce

Prevent all damage that black sources and red sources would deal this turn.

Paladin en-Vec

First strike, protection from black and from red (This creature deals combat damage before creatures without first strike. It can't be blocked, targeted, dealt damage, or enchanted by anything black or red.)