Black mask

A Black mask gives a 15% Attack and Strength boost against all Slayer task monsters. This does not stack with the effect of a Salve amulet against undead Slayer tasks. It also has ten charges that randomly lower the opponent's defence level by 3-10, whether or not the opponent is the task given. The defence-lowering ability can only be used 10 times, completely at random. Once the charges are gone, the mask and its attack and strength bonuses remain, although there is no way to recharge the mask. It requires 10 Defence, 20 Strength, and 40 Attack to wear.

It is dropped by Cave Horrors (Level 58 Slayer required) in the Mos Le'Harmless Caves.

A recent update, the release of Smoking Kills, allowed users to craft the mask into a Slayer helmet provided they had paid for the ability to make them. This update, and also the rumor of lowered drop rates by Jagex is responsible for the steady price increase of the Black Mask, from approximately 400-500k to well over 900k, due to the increase demand of the mask to create Slayer Helmets, and Slayer helmets are not tradable. However, two weeks after the update, prices can be seen dropping in the Grand Exchange Database and players are frantically trying to sell these on the official Runescape forums and for lowest market price available.