[quote=@The Omnipotent Sphere]
For summoning, could you give an example of a covenant that could be made?
[/quote]

I have not thought of exact covenants. In exchange for the Spirit's complete loyalty, it makes you commit to a certain lifestyle, habit, regular "worship" and/or requires you to give away something. That something should somehow then be seen in the character's behaviour or actions in the game.

I should mention that the spirits are nature related. Elements, forces of nature have each their spirit.

[quote=@Chronothesis]
Oh! And will summoning be a larger part of the RP than we expect? 

( Meaning, thing's like different dimensions. )
[/quote]

Can't really say what you are expecting but there won't be other dimensions and summoning itself won't be the main focus of the story.