Grand Cleric Callista is first seen during the Seekers of Truth's audience with Divine Beatrix III at the Grand Cathedral, where she compliments Cassandra on killing a drake, remarking that the Pentaghast family has lived up to its reputation. Callista is encountered again after the disappearance of Avexis. Callista orders that the templars, rather than the Seekers, be dispatched to arrest Cassandra.

It is revealed that Callista and Knight-Commander Martel are conspiring with Frenic to assassinate the Divine and other Grand Clerics at the Ten Year Gathering, so that Callista will become the next Divine of the Chantry. After the assassination attempt fails, Callista is badly injured and stumbles to Frenic for help. However, when she reaches him, Frenic stabs her with his staff, killing her. Frenic admits that he had merely used Callista for her ambition.