"Free Goblins" illustration - Illegal Magic User

I hope to create a series of illustrations for my story Free Goblins. This scene was one of the key moments in my mind, so I decided to draw it and along with a short story description below.

One night, the old wizard Scavenger was reading his favorite magical book before going to sleep in his enchanted hut.
Suddenly, His goblin slave Blin used magic to turn "his chains" into a key and a lock.
The wizard had taught him a little magic before, but goblins were not allowed to use it. The wizard was shocked.
He didn’t think a goblin this kind of creature could do something like this, Because using magic to combine new things isn’t considered low-level magic.