Character's name
Mihael Keehl, but he goes by Mello, and if Castiel uses his real name he will flip his shit ... not saying that shouldn't happen at some point, but.
Prayers
Nah, not likely to happen.
Teleportation
Yes, could be hilarious.
Telekinesis
Yes, also could be hilarious.
Sleep
Mmmmmaybe?
Memory alteration
Prrrrrobably not unless there's a realllly strong case for it.
Dreamwalking
Yes! These are a good example of what Mello dreams about.
Healing
Maybe ...
Magic
My character can be located by angel magic
Invisible
Nah, be invisible all you want.
Supernatural signature
Not applicable; Mello's just a basic (genius) human.
Soul reading
Yes!
If yes: App info here.