Achtryn

Achtryn is a demon who temporarily replaces the Slayer Master Mazchna while he is busy during the quest While Guthix Sleeps. Like Mazchna, Achtryn is a demon, though his face and proportions look decidedly human. He claims to be from the abyssal regions, where, it is said, demons on Gielinor originate from. After the quest is over, Mazchna returns to his post near Canifis, and also reappears on the NPC Contact spell in the Lunar Spellbook, and Achtryn is not seen again.

He claims that his lair in the abyssal regions is a fine place of residence, but it is good to see the sights, to meet mortals and generally socialise.

Assignments
'''Many slayer monsters have numerous variants of the monster assigned. Please check the monster's page for more specific information about the different variants.'''

Slayer Challenge
After a player has performed several slayer tasks for Achtryn, he will occasionally offer a special task in place of a regular slayer task. The player can decline to take the special task without penalty. If the player accepts the special task, completing the task:
 * Earns extra slayer experience.
 * Earns Slayer reward points, if the player has completed the Smoking Kills quest.
 * Counts as a task for the player's consecutive task count, which is used for slayer reward points.

Achtryn's special task is for the player to slay all the creatures corrupting the Fairy rings in Morytania. The player must go to each of the three fairy rings in Morytania: At each ring, the player must contact Achtryn using an Enchanted gem. If the player does not have a gem in inventory when the task is assigned, Achtryn will give the player a gem for free (even if the player has an enchanted gem in the bank).
 * near Canifis (a safe area until Achtryn is contacted)
 * in the Haunted Woods (Vampyres and Leeches are present).
 * in the Mort Myre Swamp (Ghasts and the Mort Myre Swamp effect are present; a Blessed silver sickle and Druid pouches are needed).

The player does not have to use the fairy ring transport network; simply walking to the rings is sufficient. When near a ring, the player activates the enchanted gem to contact Achtryn. The player does not get the usual choices when the gem is activated (if the usual choices appear, then the player is not near enough to the ring).

The three monsters you have to fight are a Ravenous snail (level 33) at ring, a Ravenous vampyre (level 72) at ring , and a Ravenous ghoul (level 42) at ring. The fairy rings can be done in any order. The reward for the challenge is 2000 Slayer experience and 3 slayer points.

Task weighting
The percentage chance of getting assigned a given slayer task can be calculated using the formula
 * $$\frac{w}{S} \times 100%$$

where $$w$$ is the task's weight and $$S$$ is the sum of all weights for the particular slayer master. Note that the weights of all blocked tasks, as well as tasks toggled off have to be subtracted from the sum $$S$$. Preferring a task doubles its chance of being assigned.