Crystal (strength)

The Crystal (strength) is a type of lava crystal that spawns throughout the Fight Kiln minigame after completing waves 9, 21, and 33. It can only be used in this minigame and disappears after leaving. This crystal boosts your Strength level to and maintains it at 150% of its unboosted value while lowering your Magic, Ranged, and Defence levels to and maintaining them at 50% of their unboosted values for 3.5 minutes before running out.

There is currently a glitch relating to the strength crystal. Starting from wave 34 of the Fight Kiln, the strength crystal "image" will remain on the ground if the item is left to disappear.