The Oldak coil is an Invention device that is a part of the cave goblin tech tree, which is unlocked after the quest Death to the Dorgeshuun and also requires level 70 Invention to unlock. Oldak coil costs 55 goblin currency, and is locked until the player unlocks the T1 upgrade Pestiferous components (requiring 40 Invention and 10 goblin currency), one of the T2 upgrades (requiring 50 Invention and 25 goblin currency per upgrade), and at least one T3 upgrade (requiring 60 Invention and 35 goblin currency per upgrade). It is a Magic variant of the dwarf multicannon. The Oldak coil takes up a 3x3 area of space when deployed, and it can attack targets within a 9x9 area. The experience gained from using the Oldak coil is dependent on the player's Magic XP selection in their Combat Settings.
Success in creating the blueprints earns 10,518 base Invention experience, or 52,591 experience at perfect optimisation.
The Oldak coil requires cannonballs as fuel, consuming one every time it attacks (even if it hits multiple targets), and it has a cannonball capacity of 30. When active, any enemy that is in range will be repeatedly attacked by bolts of lightning, and it can hit up to three enemies at once. It benefits from the same perks as the dwarf multicannon if unlocked, increasing the cannonball limit to 60 or 90 and allowing it to restock automatically if the player is in range.
Unlike the dwarf multicannon, the Oldak coil takes up only one space in the player's inventory. If destroyed, it will need to be rebuilt. If lost, you will receive a message stating it was destroyed but that you can reclaim it from Nulodion, located near the entrance to the Dwarven Mine south of Ice Mountain. However, it can be used indefinitely if you keep picking it up and re-deploying it when you receive the decay warning.
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patch 29 July 2019 (Update):
- The Oldak coil will no longer heal you if you have a Blood spell selected.
- patch 17 September 2018 (Update):
- Due to a bug, Oldak coils and Kinetic cyclones can now be reclaimed from Nulodion near the entrance to the Dwarven Mine, if Nulodion cannot find your registered cannon/coil/cyclone on your current world.
- patch 29 January 2018 (Update):
- Dwarven and Invention multi-cannons can now be reloaded and repaired (resetting their despawn time) by left-clicking them.
- patch 12 September 2016 (Update):
- Adjusted the message for blocking cannons in the Slayer Tower since the Oldak coil is certainly not a dwarven invention.
- It is likely a reference to the Tesla coil which produces arcs of electricity.
- When used in Prifddinas, it reads "The vibrations from Seren's song would stop the cannon from functioning here."
- Originally, it required 1,725 inspiration to discover.