How does spellbane actually work? Does it check to see if you saved vs specific spell, and if you make the save the result is the spell is 'spellbaned'?

Or, is it its own "thing" seperate from saves vs spell entirely?

I guess what I am asking is, what if anything determines if spellbane "works" on any given spell.

I am curious as to if there would be a benefit for a rager warrior to take calming the tempest. Would this make him into super-spellbane boy? what with spellbane/warcry/calming/svs gear? Or, would the additional legacy and svs spell not really have that much affect on spellbane frequency assuming that the warrior already has decent saves/warcry/spellbane up.

Also do specific spells have higher chances/etc of being spellbaned? or is it a "one size fits all"