The Zamorak cape is a reward from The Mage Arena miniquest. To receive the cape, the player must defeat Kolodion in his four guises, then speak to him, step through the nearby sparkling pool, and finally pray at the statue of Zamorak. Upon praying at the statue, the Zamorak cape will appear next to the player and can be picked up.
The Zamorak cape and the Zamorak staff are required to benefit from the Charge spell, which enables the player to hit up to 50% more damage with the Flames of Zamorak spell.
Once lost, a player can get a new cape by once again praying at the statue of Zamorak. Kolodion does not have to be fought again. Alternatively, players can purchase one from Perdu for 23,000 coins (although this requires the player obtain the cape at least once from the Mage Arena).
The Zamorak cape can be imbued with the items dropped by Justiciar Zachariah, Porazdir, and Derwen, during the The Mage Arena II miniquest to make an imbued zamorak cape. Subsequent imbues will require only the Demon's heart.
The Zamorak cape can be combined with the max cape to change its appearance by turning it into the Zamorak max cape.