Plains

Warmth

Whenever an opponent casts a red spell, you gain 2 life.

Soltari Monk

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

Order of Leitbur

Protection from black
{W}: This creature gains first strike until end of turn.
{W}{W}: This creature gets +1/+0 until end of turn.

Cho-Arrim Legate

If an opponent controls a Swamp and you control a Plains, you may cast this spell without paying its mana cost.
Protection from black

Crimson Acolyte

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

Circle of Protection: Red

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

Crown of Awe

Enchant creature
Enchanted creature has protection from black and from red.
Sacrifice this Aura: Enchanted creature and other creatures that share a creature type with it gain protection from black and from red until end of turn.

Voice of Law

Celestial Purge

Northern Paladin

{W}{W}, {T}: Destroy target black permanent.

Mangara's Equity

As this enchantment enters, choose black or red.
At the beginning of your upkeep, sacrifice this enchantment unless you pay {1}{W}.
Whenever a creature of the chosen color deals damage to you or a white creature you control, this enchantment deals that much damage to that creature.

Honorable Passage

The next time a source of your choice would deal damage to any target this turn, prevent that damage. If damage from a red source is prevented this way, Honorable Passage deals that much damage to the source's controller.

Circle of Protection: Black

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

Conversion

At the beginning of your upkeep, sacrifice this enchantment unless you pay {W}{W}.
All Mountains are Plains.

Voice of Grace

Disenchant

Red Scarab

Enchant creature
Enchanted creature can't be blocked by red creatures.
Enchanted creature gets +2/+2 as long as an opponent controls a red permanent.

Exorcist

{1}{W}, {T}: Destroy target black creature.

Starlight

You gain 3 life for each black creature target opponent controls.

Guardian of the Guildpact

Karma

At the beginning of each player's upkeep, this enchantment deals damage to that player equal to the number of Swamps they control.

Defender of Law

Sacred Knight

This creature can't be blocked by black and/or red creatures.

Freewind Falcon

Black Scarab

Enchant creature
Enchanted creature can't be blocked by black creatures.
Enchanted creature gets +2/+2 as long as an opponent controls a black permanent.