Board Thread:General Discussion/@comment-181.22.148.239-20160402045741/@comment-27755354-20160710202143

If you're referring to Skyrim's option to make a skill legendary; Once you've reached a skill level of 100, you have the option to make a skill legendary. This reverts the skill to a skill level of 15 and will return all of the perk points you've invested in it. You'll be allowed to invest the perk points in a different skill. It also allows you to level up the skill indefinitely, thus also allowing your character to level up indefinitely