Disable Helm

You target a single spelljamming helm that you can see within range and draw upon your own life energy to disable it. The affected helm instantly ceases operating, and cannot be activated again by any means until the spell ends. Both the caster of this spell and the spellcaster attuned to the targeted helm suffer 1d4 psychic damage have their maximum hit points reduced by the amount of damage taken. The spellcaster attuned to the disabled helm must also succeed on a constitution saving throw or fall unconscious for 1d6 rounds and have their maximum hit points reduced by 1 for each round they are unconscious. Nothing less than a wish can end this effect early.

This spell is inspired by page 70 of the 2e AD&D book titled Spelljammer: Lost Ships by Ed Greenwood.