This spell will give you powers of darkness and will dedicate you to Mother Darkness mostly known as Nyx and you in return you need to give your soul/blood as offering if you can't give your blood physically then you can give Astrally too in an Astral bowl.

The chant :-

Oh mother darkness make me back your son give my darkness to me back with the swords you see bring me back bring here let the darkness flow through me I must be your son

Then go to a dark place or if you can't go or don't have any place then imagine Mother Darkness covering you with her darkness and then say 

Oh mother darkness make me your son give me (ask what you powers you want not super powers but like spiritual abilities like empathetic abilities or you can even ask for Astral weapons ) and in return I give my soul/blood as offering .

After it she will come to you and give you what you desire and bless you as her son .

Warning :- The offering must be given to Mother Darkness and it depends on what you desire and what the offering can be if you have a heavy desire then your soul has to be given and if normal you can give blood and if you can't physically you can even give Astrally too in an Astral bowl and if you won't give any offering the spell will be null and void and on full moon it will be more effective .

I got a blade and some powers that I can't explain.

Many blessings for the spell .