So one of the goals of Tartaros was
that they would activate Face, which would then wipe out magic all together from the world. Or at least from the continent, which would be quite helpful for them as they don't use magic, but rather curses.
However, it is clearly stated that the strongest members of Tartaros
are all demons created by the dark mage Zeref himself. Even if they don't use magic, they are just Zeref's living magic.
Doesn't that make them vulnerable to Face? Wouldn't it kill them?