Destroy Helm

You target a spelljamming helm and utterly destroy it. If a helmsmen is seated in the helm when it is destroyed, they also suffers 1d8 lightning damage and must succeed on a constitution saving throw or fall unconscious for 1d4 rounds and suffer 1d4 days of magic death. While afflicted with magic death, a spellcaster cannot regain expended spell slots. Creatures immune to disease are unaffected by magic death, and it can only be removed by greater restoration or stronger magic.

This spell is inspired by page 71 of the 2e AD&D book titled Spelljammer: Lost Ships by Ed Greenwood.