The Mask of Stench is a slayer mask obtained from Treasure Hunter, or from the Shattered Worlds reward shop for 63 million anima. It is associated with the aberrant spectre slayer monster. It gives two free teleports to the monster per day, acts as a nose peg for safely killing aberrant spectres, as well as giving extra Slayerexperience while on a Slayer task of this monster and double drops on every tenth kill. The extra experience and drops are lost when the mask reaches a certain kill count, at which point it can be transformed into a helm.
This mask does not function as a face mask. If slaying in the Pollnivneach dungeon, the player will have to use the mask's teleport or wear different headgear until they reach the spectre's area.
Once per day, while wearing the relevant mask, the next assignment the player receives will be aberrant spectres. They will still need to go to a Slayer Master that normally assigns these creatures (Kuradal, Sumona) – if they do not, the player will be told which Slayer Master assigns them. This does not work if they are in the process of setting up a co-op Slayer assignment.
Twice per day, this mask will teleport you directly to a location where aberrant spectres can be found.
The mask confers the same damage boost against aberrant spectres (but only while on assignment) as the Slayer helm.
Killing aberrant spectres while wearing this mask will grant additional Slayer XP equivalent to the Slayer level required to fight them, in this case 60 experience. This is given regardless of the current assignment the player has and in addition to assignment and/or contract xp. The XP awarded by the mask can be boosted by items.
Killing aberrant spectres while wearing the mask will grant a double drop for every 10th kill. (This includes the Aberrant Spectre Champion's Scroll if it is dropped on a 10th kill.)
Every creature killed is tallied, while the mask is worn. Each mask has a set amount of kills assigned to it that, once reached, "uses up" the Slayer XP and double drops effects, and turns the mask into a helm. The kill count continues to be tracked beyond this point, up to 1,048,575 on the item's tooltip. However, only up to 999,999 can be displayed to others with the "check kills" option.
A right-click option outputs total kills of that creature. If the helm has yet to be unlocked, there’s also a message to say how many more kills are needed to do so.
After the helm version has been unlocked, the player is free to switch between it and the mask version, as a cosmetic preference only – this does not restore the Slayer XP and double drop effects to the mask.