Proctiv's breach crystal sphere

Proctiv's seal crystal sphere was a powerful arcanist spell that permanently shut off a whole crystal sphere against access by spelljamming ships.

It was actually the reverse version of the name-giving spell Proctiv's breach crystal sphere, which removed an earlier-cast seal crystal sphere, thus opening up portals through that crystal sphere again.

Components
Next to verbal components, the material component for this spell was a spelljammer with a tonnage of 100 tons, including a major helm.

History
This spell was developed by the Netherese archwizard Proctiv in 1808 NY (−2051 DR). As one of the epic spells of Netheril, it could no longer be cast after Mystra changed the rules governing magic after Karsus's Folly in -339 DR, the Year of Sundered Webs.