Adventure in Limbo

Hey everyone!

Just posting here to get any advice if anyone has run a similar campaign, but my group is just about to finish a modified version of The Lost Mines of Phandelver for 5e. One of the party is a githzerai who has lost their memory, and depending on the outcome of the fight, I was thinking of a portal to Limbo being created to where either the Black Spider escapes to or where the being behind the Black Spider is imprisoned. This would also allow the exploration of the githzerai’s backstory.

Has anyone ever done sessions in Limbo? How hard would that environment be for 5 Level 6 characters? Is it a good place for an adventure to take place? Let me know if you have any tips!