Ok here is another bit of what I think
On top exist the Deities / Gods (Very powerful)
Good Beings (Sort them for highest to lowest power)
High Powerful Faires. Like Blue Fairy. Theirs
Known Abilities are:
http://supernatural.wikia.com/wiki/Fairies plus she could have precognition powers
http://powerlisting.wikia.com/wiki/Precognition
or could she being told about the future by the deity theirself.
Fairies (like Nova) http://supernatural.wikia.com/wiki/Fairies
Magicians, sourcerers (like Merlin). Probably Emma, Henry, Snow.
Mortal beings
Bad Beings (Sort them for highest to lowest power)
Devil Being (Like Loki for example, he can ShapeShifting).
The Dagger. The Devil Being put part of his powers in it and he created the Dark One in first place using a mortal being
Dark Fairies (Maleficent)
Rumplelstilskin / Dark One (Ringleader visible) is the tool of the devil being. He can precognition power after the Seer (The devil shapeshipted as her) gave to him.
Cora and less powerful Regina.
Hook (He could ripped hearts)