Charms are specific to each Profession and can be unlocked through the Skill Tree. They can be identified as the squares on the image.
Charms can be used while in a Fortress’s lobby in conjunction with other Wizards/Witches or Foes through drag and drop motions. Charms are different from Skills (which increase your base statistics) as they are specific to Fortresses. Some will affect Allies, while others will affect Foes.
For instance, in order to use one of the charms you have unlocked, you would simply drag one of them (located at the bottom of your screen, up to four of them), and slide them onto the desired Ally or Foe (depending on the purpose of your Charm).
List of Charms to come soon.