The Shrines of Body, Mind and Spirit are in the east tower.
At the Shrine of Spirit, Ieros asks what you would do if your extra souls deserted you? Three souls then separate from you: Asias the Cabalist, Nyol the Sentinel, and Ekkehard the Shaman. You are not able to attack. Nor, do you need to.
At the Shrine of Body, Ieros asks if you trust him with your body. A Crazed Oni appears and mauls you, but when you reach about 10% your damage slows then stops for a time. Do not let up. Pound him for all you are worth and you will barely survive!
At the Shrine of Mind, Ieros asks if you can trust your senses. You are transformed into a Pyrkari and attacked by a Temple Guard. When you defeat him, the illusions drop and HE is a Pyrkari! Beat him back down again.
Go to the outer room of the north tower and use the Travel Shard to travel up to the Temple Seat and talk to Ieros.