The Chaos Fanatic is an insane mage demi-boss found within the deep wilderness, west of the Lava Maze.
With a combat level of only 202, the Chaos Fanatic is a low-level boss suitable for lower levelled players. His drop table is not particularly good apart from the Odium and Malediction shards, which themselves are now quite cheap.
The Chaos Fanatic has one particular attack which you need to watch out for. this is a green magical attack which will explode at your feet and deal AoE damage. When you see this attack incoming, you should run a few squares in any direction to avoid the splash damage.
The most common tactic to use at the Chaos Fanatic is to use a Ranged setup, making sure to only have a maximum of four expensive items to ensure you can keep them if you are killed by a PKer.