You could just mod the magnetic cloud ability...
Just wrap the disabling buff in a containing buff that prevents reapplication on removal. Then remove the disabling buff with one applied to the constructors. If you set the disabling buff to remove the counter on spawn, and set the counter to remove the disabling buff on spawn, it will work with almost no overhead. Just a passive that normally does nothing on the constructors, two instant actions that only fire when needed, and an extra step to the magnetic cloud ability.
