What happens if you tattoo a Changeling?
Cheers.A changeling can alter its appearance. It can conceal existing scars or tattoos, or add new ones. So the tattoo will exist, but the changeling can hide it.

— Keith Baker🔜DragonCon (@HellcowKeith) July 27, 2019

I have a magical mark in my campaign and one of my players is a changeling. I had this specific one be unable to just be hidden so instead I had a talented Skindancer teach her to weave the mark’s shape around her body. That makes sense to me!

— Keith Baker🔜DragonCon (@HellcowKeith) July 27, 2019