To upgrade the helmet, visit any Slayer Master with the mighty slayer helmet equipped and the corrupted gem in the inventory. A new option will appear in the Slayer points rewards interface, listed as "Full Slayer Helmet Upgrade (4)". Upgrading a mighty slayer helmet the first time costs 1000 slayer points, and the corrupted gem will be consumed in the process. After upgrading to a corrupted helmet the first time, any additional mighty helmets will only cost 100 slayer points to upgrade, but will still consume a corrupted gem.
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