I agree it's cool by having it's own way of being active instead of the regular point and click AoE. Maybe to make up for this shortcoming give players who enter the AoE a buff of some kind.

Diurnal effect gives players a regen with the 150 potency while under the dome, but if they leave they switch to a 100 potency regen for the remaining duration.
Nocturnal effect gives players, under the dome the same 10% damage reduction; if they exit the dome, switches to 7 for the remainder of the duration.

Something like that.