Overgod

Each Sphere can have only one Overgod. These beings do not need worshippers and their power relates only to how prosperous their world is, which can have dozens of conditions. A sphere can still exist and function without an Overgod but there must be True Gods for it to function, otherwise, the sphere starts to break. An Overgod rules over the sphere in Palace of the Overgod which is also the North Star for the mortal beings. No God can enter the Palace without the permission of the Overgod and if there is no Overgod, it is an empty space, waiting to be filled.
Over time the seat can be filled by one of the Greater Deities. If a Greater Deity is supported by 2 more of its kind, then it can start the process of becoming the Overgod. This can be detrimental to the world and even can cause a shattering event, if not done properly. Also, other gods won't be kind of having a ruler (when they had none before) and might stop, intervene or corrupt the ritual. If it succeeds, the new Overgod can create a new rule, change or remove a previous one. These rules govern the sphere and godhood, so almost all gods would want access to that kind of power. However, the new Overgod can do this only once in his entire (god) life. If he ascends to a Cosmic God or descends, he won't be able to mess with the rules. These are the cosmic rules of governing spheres.