When a cyclossus first appears, it can only be attacked by the player it is after, and nobody else. If the original player breaks off combat with the cyclossus (by not attacking it or being attacked by it for 10 seconds), the cyclossus will walk around the room taunting other players by name, and calling out things like "Your mum has two eyes!" and "Two-eyed freaks! Think you can take on Cyclossus?" During this time, any player not in combat can attack the cyclossus, not just the original player.
The cyclossus possesses a special move which shoves the player back several squares and knocks the player down. The cyclossus then follows this move up with a magic attack that looks like a tiny lightning bolt. This always hits, damaging and stunning the player. Since this prevents the player from eating or drinking potions it is advisable to have Freedom and Anticipation on your action bar. It is recommended to stand near a wall in the warriors guild while fighting Cyclossus, to stop it from pushing you away. This will do two hits; the pushing hit that does not hurt a lot and a lightning bolt that also does minor damage.
The melee attacks of a cyclossus are much more accurate than those of a regular cyclops. The Protect from Melee prayer blocks some melee damage and is recommended for players who can use that prayer. This prayer, however, does not block the special move or magic attack of the cyclossus. Harrallak does not allow Ancient Curses to be used in the Warriors' Guild, so Deflect Melee and Soul Split cannot be used. Ancient curse users should switch to the regular prayers if they wish to use prayers in the room.
Some drops will be noted and in a higher quantity if "Use multiple token types" is selected when entering the room. For example, the player will always receive 2 noted Big bones when killing a cyclossus.