Theres a cave in Felwood filled with level 54ish elemental mobs, just north of Irontree Woods:
Here's an up-close pic of the cave:
There is a lip going across the left side of the entrance, which basically acts as a wall. If you are flagged in combat with a mob, and move to the opposite side of this lip, the mob will have to go around the rock in the center of the entrance in order to get to you. All you have to do is move back and forth across this lip before the mob gets to you, and you will never be touched:
in other words, this works like the dire maul west exploit on the ramp jusst before tendriss