Counselors are a pain in the ass. It has been my experience that they will usually show up, in large numbers, along with some Succubi and Knights. They teleport all over the place, and cast Charged Bolt to cover the ground with lightning. Your best bet is to fight them up close; watch the ground for lights, as this is how you can track them. Once they appear, start swiping/plucking arrows/casting spells.

The Warriors probably have the easiest time with these guys; just walk up to them, follow them as they teleport, then whack 'em. The Rogue and Sorcerer, on the other hand, may not have as much fun, as these guys have different resistances and immunities. Its best for a wizard to use Stone Curse to freeze them, and then the Rogue to take them out with her bow.