The Oh My God squad doesn't work so well anymore in 4th ed.... still they would be higher in the target priority. I guess that would be the best way to go about it but i wuoldn't suggest using an avatar at all, with their NFW, they have a high enough S to effectively wound it, and an avatar's save isn't exactly impressive. Getting shot at with Psycannons would also ruin an avatar's day, so a teleporting squad with dual psycannons can put dirty great dents in your avatar. The charachters are even worse, with anti daemon skills and other things, things like the force weapon 4++ save having Grand master.