The interesting Hero/Facility idea

[Suicide Junkie]

The one per system effect is only for those particular abilities.

Any extra abilities on the facility which are not inherently non-stacking across the system will stack, and are thus not "one per system effective"


If you keep your heroes to using non-stacking, system-wide abilities, then you'll get only one-per-system effective for each ability, but you'd still be able to have both a system-damage-increaser and a system-shield-booster hero facility operating at the same time.