The Invasion of Time
Presta was a member of Nesbin’s group of Outsiders.
Like all Time Lords, Presta was taken from her family at the age of eight for the selection process in the Drylands. Staring into the Untempered Schism as part of a Time Lord initiation rite, Presta reacted by running away from what she saw in the Schism. (A Brief History of Time Lords)
Presta helped the Fourth Doctor and Leela defeat the Sontaran invasion of Gallifrey. (The Invasion of Time)