The Chaos Elemental is a dark cloud with six tentacles. The Chaos Elemental is immune to venom —any items that are able to inflict venom will inflict regular poison instead. It has a combat level of 305 and is not a very hard boss to kill! You can find Chaos Elemental in the Magic Spellbook - Boss Teleport - Chaos Elemental.
Using "SoulSplit" (Level 92 prayer required) makes this boss pretty easy. If you use a fast hitting weapon like a; Space Jam Sword, Ice Katana, or Soulflare this boss is not hard to kill. However it make take a long time depending on armour. The best gear to use at Chaos Elemental is Shadow Torva, America Torva, America Pernix. Anything else might take to long!
Since the Chaos Elemental is a boss, it is included in the Soul System, converting all common and uncommon drops into souls. TheChaos Elemental, along with all other NPC's in Dreamscape, drop Key Fragments and Treasure Chests.