[Deathblob]

I think when you have A and N domes up, the A domes stop spells until they all break. The spell that breaks the A dome gets to hit the prov. Once all the A domes break, then the N domes have a 40% chance (just one, doesn't matter how many N domes you stacked) to stop a spell. If an N dome stops an F spell, it can break.

If you have F or W domes (and probably B), these operate in parallel and blast the caster whose spell may or may not have happened to have been stopped by (or bypassed) a A/N dome.

I'm not sure how S domes stack with A and N.

The only way I can figure out how to visualize stacked A/N domes is that only one A/N dome can physically manifest at a time. The stacked domes are just waiting to materialize once the currently manifested dome pops.