"Theresa is the seer who resides in
the Tattered Spire, far off the coast of Albion.
Theresa played an important role in your father's
defeat of Lucien and subsequent rise the power.
Her motives are unknown, as are her true powers and identity.
Theresa will escort you along the Road to Rule
and be there to cast judgement when the time comes."

She will bring you up to speed on your progress towards usurping Logan,
and then you'll have an opportunity to gain new abilities from chests you couldn't access before.

Game Strategy Guide