Description from the publisher:

A dark void has opened, and undead creatures are attempting to enter our world. You have come together as guardians who must work together to force the undead back through the void. However, the longer it takes, the stronger the undead become, threatening to overwhelm all.

In The Banishing, players collect cards from the Void to form melds to cast unique spells and effects in an effort to complete the ritual of Banishing, which will hurl the undead back through the Void. Players must work together to create those melds, as well as to protect and heal each other from attacks by the undead in order to succeed.