Ruby Medallion

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

Sol Ring

Mountain

Pearl Medallion

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

Swamp

Extraplanar Lens

Imprint — When this artifact 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.

Jet Medallion

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

Island

Emerald Medallion

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

Forest

Sapphire Medallion

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

Plains

Gauntlet of Power

As this artifact 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.