Has anyone figured out what "defeat your shadow self" means?

[Kuality]

so im working on completing all the achievements for leaf our newest character and im having trouble with one in particular that being the one called "face yourself" it tasks you with defeating your shadow self as leaf. I am a bit confused by what it means by shadow self, is it a new hidden boss that replicates your character and you have too fight it? or is it an item that will spawn copy's of you're self that you can dmg and eventually defeat.

Any help would be appreciated if you happen too know what its referring too?

[Lindyhop]

Time has a new summon power that summons a clone of yourself. In Act 3 some mobs and the final boss can charm your summons and make them aggressive towards you. During that aggressive time, they can be hit and killed. So kill your clone and that's your achievement.

[Kuality]

thank you very much i was so confused by that achievement