Sharktoothed longsword from the Crushing Wave Reaver in Princes of the Apocalypse, usable by PCs?

Princes of tht Apocalypse player turned to stone…

How much time would you say passes between Princes of the Apocalypse and Storm King’s Thunder?

Elemental beacons

Nervous DM?

To permanently kill off an Prince of Elemental Evil, would one have to kill it on its own plane?