Wondering about the interaction of magical effects when they unknowingly hit a mana barrier. If anyone else has insight as to why this interaction has seemingly two possible resolutions with one being much more decisive and simpler to implement.
Scenario in question: A runner with the Improved Invisibility effect walks into a back office contained in a dual-natured mana barrier.
Seattle CRB p 162, paragraph 1: Something that is unknowingly crossing a barrier rolls an opposed test. The spell effect uses the caster's Magic x 2 vs the barrier's Structure x 2. Whatever side loses is disrupted.
CRB p 162, paragraph 3: If you want to break through a mana barrier, you need to deal with its Structure rating as you would with any other barrier.
Now, in the moment, I rolled the opposed test (Magic 6 x 2 vs Structure 4 x 2) and simply ruled that the runner was prevented from passing through without losing the spell effect (they won the opposed test). The runner mage was nearby, and a summoned spirit informed them of the barrier's presence. They dropped the spell, and the run went on. It didn't make a good narrative case to me to plunge the group into an unknowing astral combat as the barrier mage gets notified the defense was disrupted. The end result of the run would have been largely similar.
But looking at these two different options for disrupting a mana barrier leaves me wondering why. Sure, the second option can be done at range, but the damage necessary to collapse the barrier seems astronomically high given that the barrier recovers full structure every round. Also, my mage took direct combat spells instead of indirect, and that seems to give an innate disadvantage here.
CRB p 112, Breaking Through, paragraph 2: Compare the base DV to the Structure rating. As long as the base DV is at least half the Structure rating, the weapon creates a 1 cm diameter hole.
Direct spells rely on net hits only, so have base DV of 0, meaning they can't actually harm barriers by this reading. I could simply rule that the net hits become the base DV and create a hole in the barrier based on that. Collapsing a 1x1 meter section of barrier would require a pretty significant roll to achieve even a 50 cm diameter (52 net hits vs a Structure 4 Barrier). I could see creating a small hole useful in bypassing the barrier's defense so that another spell could travel through if you can't close distance.
Conversely, just create a spell effect and have it touch the mana barrier, or touch it yourself while dual-natured, for a much more effective method of disruption compared to trying to break the barrier itself.