Secret Agent Kollin:
Before you can sneak into that place, you must transform yourself using a special spell.
Of course, what's really important is staying alert during the transformation. It's not perfect, so you will have to be careful when you interact with others inside the Sanctum.
Moreover, there is a time limit on the transformation, so you will have to move fast.
in fact, you'll ned to use a special skill to you move faster.
"What skill?"