Aya is a Slayer master who replaces her brother Turael during and after the events of While Guthix Sleeps. According to her, she originally was the Slayer master in Burthorpe before her brother, who was a thrill-seeking adventurer at the time, and that he took over her duties after Spria was born.
Being the same as Turael, players can speak to Aya to change a slayer task from another master to a less difficult one, provided that it is not a task that she can assign. Moreover, she will issue a change only once per task type. Warning: After a task change is processed, your task streak will also be reset to zero.
Because the tasks she assigns are relatively easy, players often use Aya to boost their Slayer reward points. This is accomplished by completing every 50th task with a Slayer master that gives a lot of points per task, such as Konar quo Maten, and using Aya for the rest of the tasks to get to every interval of 50 more quickly. You can do this every 10 tasks instead but this is not recommended due to the amount of unfavourable tasks that can be given, unless you use a different Slayer master (other than Konar).
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Trivia
In Runescape, Aya's niece Spria served as Turael's replacement for Burthorpe Slayer Master after While Guthix Sleeps. However, Spria had already been added prior to the Old School Runescape release of the quest as a separate Slayer Master. Because of this change, Aya was created to be Turael's replacement in Burthorpe instead.
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