Try making a regeneration aura (Unholy Aura if I'm right) that targets buildings / mechanical units and no organics?
Doesn't unholy aura increase current regeneration rates by a %?
So a building with a 0.00 regen rate wouldn't regen? or would the aura add a .xx% regen rate to all things affected?
Unholy Aura's life regeneration percentage does not base itself on the unit's life regeneration.
It simply increases the regeneration like a Health Stone, Keg of Ale, or Ring of Regeneration.
However there is a boolean flag I think that once enabled makes it increase regen as a percentage (same with the mana regen aura) but this is by default disabled.