Credits: Sam; Xtrmsk8er108; Aserwarth; Ryan P J; Dark Blade75
To access Braindeath Island you must have begun Rum Deal
and speak to Pirate Pete located north-east of the Ectofuntus. Killing Fever spiders will grant you 40 slayer experience.
You must have 42 slayer and slayer gloves to kill the Fever Spider. If you do not use slayer gloves then you will become diseased. (Just like the disease from the Zogres in the Zogre Flesh Eaters Quest.) You will also be hit for 10 damage every attack. There are safespots in the north and south halls that you can use for range or magic. The spiders will be too big to get through.
A bunch of legs, eyes, and teeth.
Fever spider body, Grimy kwuarm