Divide the raid into two forces, place one in front of the electric fence to the east, and one in front of the electric fences to the north. The north side has 2x as many sarnaks as the east side. We would use Fortitude and deflection rotations on the waves. The sarnaks can be mezzed, they can be decap/assassinated/headshotted, so balance those classes accordingly.
After the giant emote goes out, run the raid to the south and kill the giants. Already have the 4 casters who will ride the mounts planned out, so they can immediately mount up as the giants spawn and start to knock the sarnaks out of the sky. As soon as the 3rd giant dies, run the groups back to their starting spot. Once the bombers are knocked out, 4 sarnaks will spawn in the north and 2 will spawn in the east. Engage them in the field beyond the electric fence.
Then finish off Gorenaire as normal.