Suppose that I'm using the Targeted Dispel version of Greater Dispel Magic against an enemy with multiple spell effects active - do I make a separate dispel check for each effect I'm trying to dispel, or do I make one dispel check and apply it to all of them?
The description of targeted version of the spell says:
Targeted Dispel: This functions as a targeted dispel magic, but it can dispel one spell for every four caster levels you possess, starting with the highest level spells and proceeding to lower level spells.
Targeted dispel magic's description says:
...You make one dispel check ... and compare that to the spell with highest caster level... If successful, that spell ends. If not, compare the same result to the spell with the next highest caster level. Repeat this process until you have dispelled one spell affecting the target, or you have failed to dispel every spell.
The only difference with targeted greater dispel magic is that you dispel more spells if successful.