ultimate house of horror

Every mechanisms needed a core, it was either a battery or something that store the energy of that mechanism and keeps it running. The dome was equally like that. It was not a magic spell that just needed to be recited and would put itself up, even magic spell makes use of the casters body as it's core, for this reason, mages venturing into the arts of black magic were at a risk of having their bodies damage from the strain of energy they would have to undergone.