stonegod
Spawn of Khyber/LEB Judge
Dispel magic can be used to dispel any ongoing effect. Against those on a creature, one can have rods of absorption, spell turning and the like to help protect against it. Other than finding ways to increase CL, however, is there a defense against someone dispelling an active spell you cast that is not centered on you (such as a wall or other ongoing effect). Something like spell lock from the good old Master of Magic PC game.