Be the Fool and the Hero consists in freeing Mastaba, and imprison him again. As it's one of the most difficult quests to be done, and as only few people did it, I don't want to give too much hints, to keep some interest in the game.

To free Mastaba, you need to find a certain black figurine (20.000 XPs). You must USE (5.000 XPs ?) the black figurine in the proper place prior to go and free Mastaba (20.000 XPs ?), by fixing some machines.

When Mastaba is free (you are the Fool), and is actually messing Altaruk and Defiled desert, you must find a white figurine (5.000 XPs ?). You need to USE it (0 XPs) in the proper place too.

Then you will need to find the Tome of the Time (maybe you can check that conversation as a hint). It's the only way to really kill Mastaba. You can defeat him in Altaruk, but if you don't have the Tome of the Time, he'll be back again and again. If you have it, you will be able to truly kill him (or send him back to the containment sphere, rather) and become the Hero. The Hero will be highly rewarded for this deed, with XPs (100.000 in 1.6!) and fame (an annoucement is made in Altaruk when Mastaba is defeated, and the town crier will talk of your heroic actions for a time).