Butt wings? Really rito?

She would have three pair of wings like Kayle, but since she's a fallen angel and doesn't fly anymore, their wings stay down. And Kayle's wings are butt wings too.

For those that don't know what the OP is talking about

https://3.bp.blogspot.com/-6TDj8ks6u6I/XGrgdray1JI/AAAAAAABO3w/sDKHFSA2LSQtj506sDKX2bW2SmJIis7swCLcBGAs/s200/1.png

Idk, I'm not really against it, but I agree that it is a little odd.

Anatomically, they would be more decorative than functional for flight.

No , look again. Their wings are placed in almost the same places . Morganna just has hers folded and arranged differently, which gives it the mistake of looking like that.
They are in her lower back , just like Kayle especially if you look at Kayle's recall near the ned of the teaser.

Morrigan says hello.

{quoted}

I don't hate everything about the Morgana rework but wtf is with the butt wings?

Dude, you gotta know your lore. Butt wings is a common go for demonic/evil characters. Take Darksiders for example, all the demons have them. It's sort of symbolic of their journey to evil.