Swamp

Mountain

Emerald Medallion

Green spells you cast cost {1} less to cast.

Pearl Medallion

White spells you cast cost {1} less to cast.

Sol Ring

Gauntlet of Power

As Gauntlet of Power enters, choose a color.
Creatures of the chosen color get +1/+1.
Whenever a basic land is tapped for mana of the chosen color, its controller adds an additional one mana of that color.

Island

Jet Medallion

Black spells you cast cost {1} less to cast.

Forest

Extraplanar Lens

Imprint — When Extraplanar Lens enters, you may exile target land you control.
Whenever a land with the same name as the exiled card is tapped for mana, its controller adds one mana of any type that land produced.

Ruby Medallion

Red spells you cast cost {1} less to cast.

Plains

Sapphire Medallion

Blue spells you cast cost {1} less to cast.