Shadow_D_Monarch3
A suggestion is that the MC improves his darkness and other powers, for example: swords, chains, constructions of darkness or an armor that he creates on his body which he can change the size of. It is similar to the darkness of Meliodas from Nanatsu no. taiza another thing is that darkness is mass that can generate gravity like the black-bearded yami yami from one piece. As for the earth, he could control the sub arts of the earth like in the world of Avatar the Last Airbender. The souls could be used like Big Mom from One Piece does, and last but not least the bones could be used as kimimaro from Naruto's Clam Kaguya.