Oath to the League

Talk to the Soaked Family at the League ship, go to Novograd, and meet Aidenus in his tower on the main square.

I don't think we will ever meet again, my best disciple. Your path is dangerous and thorny, but I believe that you will walk it with your head held high and won't brring your ancestors to shame. Remember that you are a Priden! And Pridens never yield to destiny - they forge it with their own hands, eysh!Go to Nezebgrad, free Priden. I have already sent a massage to the ship's captain. Meet Aidenus and tell him about the spawns of the void and their servants in the Holy Land. May the ancestors' spirits be with you!Farewell!

A Priden? How interesting... Are you the one that has crushed a band of demon-worshippers on Howlem single-handedly?
I'm sorry, I didn't introduce myself. My name is Aidenus, and I'm the Great Mage you are looking for.
Yulia and Sebastian have already told me about the incident when our embassy turned into a battlefield, and the events that followed. So I am happy that you are willing to swear allegiance to the League! I hope one day the rest of your people will join us, too.
But for now - welcome, friend! We need decent warriors in the Holy Land!