Sebilla's Tattoo Needle (Divinity: Original Sin 2)

Guys, hello everyone! The question is for people who know this game like the back of their fingers. Tell me, Sebilla has some kind of incomprehensible - "Tattoo needle". Except for Sebilla, no one can use this needle. If you use it by Sebilla, then there begins a dialogue with answers, etc.

For what and what is the point of this needle? Should I apply it or not?

Thanks in advance to everyone.