Board Thread:General Discussion/@comment-33822595-20171211223600/@comment-31928405-20171211224930

I think it could be something like Cosmina was. One day it was a person, but Dorothea change it to monster. Dorothea likes doing experiments on people.

I just saw it on internet, it's in chapter 60. She used something like alchemy (similar to Fullmetal alchemiststyle) to summon this monster.