Unlock towards the end of Chapter 3
Takes place in the Mage School
Switch to Ivo.
Go back to the school.
I have a delivery for Chantal van Buren.
After the conversation is over, use the speaking doll (given to Ivo by Wilbur) on the Troll. As a result the troll should plug his ears.
Go back to the two-headed ogre’s location.
Walk all the way to the left and use the fireplace travel powder on the fire.
Owl, worm, and rat.
Look at the books.
Talk to the books.
Ask about ghosts.
Go in to the entrance hall.
Use the magic slate on the staff room door.
Look at the jar containing the frog to get Arch-Mage Alastair.
Leave the staff room
After 'Leaving the staff room' the achievement will unlock