I broke into ALL the high security vaults at the Counting House (lol).
One of the vaults belonged to Gortash. He wrote a memoir called: "The Astral Prism Heist." In it he details how the dead 3 recruited the Emperor to help pilot the Nautiloid and steal the Astral Prism. I took a screenshot, so in Gortash's own words:
![[Linked Image from i.ibb.co]](https://i.ibb.co/KGsDnxV/Astral-Prism-Heist.png)
7. The Gith'yanki know that the stolen artefact is on that particular Nautiloid and follow it through all the planes to retrieve it. How did they know it, and why couldn't they prevent SH from obtaining it previously [?]
I *believe* the Astral Prism was an exchange between Vlakkith and Raphael (or another Devil). At the end of Act 2, when Emperor asks for your help against the Githyanki Honor Guard, to the left of the portal is a gith disc. If you read it, this is what it says:
![[Linked Image from i.ibb.co]](https://i.ibb.co/pnPmHyg/Regal-Devil.png)
I believe the "Devlish Man" is Raphael, and the "Regal Queen," is Vlakith. I *believe* Raphael gave Vlakith the astral prism, in exchange for the Orphic Hammer.
6. Somehow Shadowheart obtains it. Where ? How did she manage ? Was this before or after the emperor entered ? [?]
Shadowheart pockets the prism, in the same room where we free her in the prologue. I believe the Emperor is the Mindflayer who glances at us eye-to-eye in the prologue and then levitates us to the ground.
I haven't found finite proof of why the Sharran's are after the astral prism. I skipped the rat quest in Act 2. I wouldn't be surprised if someone pops up with Viconia's diary.