The Needle is an Elder Artefact which featured heavily in the spin-off game Runescape: Idle Adventures, where it was prominently used by its main character. It was first mentioned in "RuneScape" by Jas during Sliske's Endgame.
According to Saradomin, the Needle can be used to unravel Time itself, creating Threads of Time out of concentrated anima from that reset timeline. These threads can then be woven back into the tapestry of existence, growing fate itself. These rewoven threads can then be used to create more of themselves as the anima of the world is once again increased in this reset timeline. This creates a cycle where the world's anima gradually and purposefully restores and improves itself with each reset.
The Threads of Time can also be bound with the corrupting influence on the world caused by undead monsters. As these threads are woven back into the tapestry, the corrupting influence is permanently removed from the world.
The Needle, like all other Elder Artefacts, were created by the Elder Gods to be used as tools in their attempt to create the perfect world Gielinor. After the creation of Gielinor, the Elder Gods started their slumber below the surface of the world, awaiting the next great revision.
Buried within the heart of the White Wolf Mountain, the Needle was among the majority of the artefacts that were left behind on Gielinor.
After the mortals and the young gods arrived in the First and Second Ages, many of these artefacts were found and claimed. However, the Needle remained undiscovered throughout most of Gielinor's history. The god Saradomin was the only one able to sense its presence on Gielinor, thanks to the properties of the Elder crown, but he was never able to find it.
After Guthix's death at the beginning of the Sixth Age, the Anima Mundi of Gielinor destabilised. The conflicts of the gods that followed caused many wounds to appear in the world in the form of energy rifts.
This caused the Needle to create an avatar. Not knowing who they were, they travelled around Draynor village, Lumbridge and Falador. Helping people with their problems, and teaching them new skills before eventually being drawn to White Wolf Mountain.
There, they were greeted by Saradomin, who discovered the location of the Needle when it created its avatar. He observes as the protagonist obtains the Needle and first uses it to unravel time, and explains his theory of the Needle's function. He then asks them to help him and his followers by removing the corrupting influence of the undead, and to increase the strength of the White Knights.
The protagonist continues to wield the Needle, increasing and healing the world's anima by helping the people of various cities.