Rhan-Tegoth (Patreon)

The final piece was held by a creature completely alien to you. A hyper intelligent monster whose physic abilities made him nearly impossible to beat... but just like all super-intelligent creatures. They were undone by something incredibly stupid. 

You won't go into details, but sufficed to say he never saw it coming. 

With the last piece of the puzzle, your guide who seemed more nervous than ever directs you to head towards a vast pyramid. There he explains with the pieces of the artifact I will be able to request passage back to my world...