By Invitation Only
Deshaan's Academy of Magic, Shad Astula, trains only the most promising mages to become leaders of the Ebonheart Pact. However, the Academy only accepts those who've received a special invitation.
Acquire a Shad Astula Invitation
If I want to visit Shad Astula, I need to acquire an invitation. Maybe I can get an invitation from one of the students waiting along the docks.
Find Arch-Mage Valelyn
Somehow, the Arch-Mage knows I arrived at the Academy. He wants to talk to me in the main building.
Repeat the Sequences of Lights
I watched the sequences of the lights. All I have to do now is touch the orbs in the same order.
— game journal
To get an invitation, the player must speak to the people around the dock. It possibly is easier with the skill persuade or intimidate, else one also can challenge them to a duel.
I'm not sure if the light sequence is for every player the same, but for me it was:
I hope you got enough imagination... but the lights are almost arranged this way.