The multiverse also contains infinite concepts,
All governed by the laws of creation. Also Gladsheim aka Reinhard's castle is so big that the realm upon which the Multiverse rests is but a mere chessboard into a single room,the castle is also infinite in size,containing "endless battlefields". It is also consistently referred to as a multiverse,outside the multiverse(Referred to as the mortal realm)between reality(the multiverse) and unreality(the singularity).
Once a God is killed,
he is erased from existence,this realm is beyond the concept of time and once Marie took the throne at the end of Rea route,she could bring back people from there. Once a God reaches the throne and challenges the God himself,the throne becomes a blank state,as a singularity is created and threatens the God's existence,this makes the throne chainable to the opponent's domain. Once Marie took the throne,Mercurius' multiverse was just one out of all the infinite multiverses that Marie brought. To reach the throne,you must be equal to the throne God as implied when it was said that Mercurius was finally on the same stage as Reinhard and Ren, and when it was said that they were on equal grounds. When a throne God or the challenger kills the opponent,the loser's corpse can be the foundation and base of the new world. Throne Gods cannot enter creation as they are boundless in comparison to everything below,thus using shadows to enter creation and the singularity, These shades are mere mirages,illusions of the throne God,this since they are mere fragments of the fantasy of the throne God,being a mere "illustration" of the throne God,implying that it is just a drawing of God that can never reach the level of the actual God. The throne God governs the whole of the singularity. If any God dies into the singularity,nothing will happen to those related to him/her,even the world is killed,everything,even the God's copy,this if the God dies outside of the singularity.