This is mostly a staging point for my ideas.
The Amalgam Realm, otherwise known as the Delve, is an utterly underground plane that possesses a strange form of sentience that draws other creatures and such into a vast testing ground. Gods exist; they are not entirely mortal but let there be no mistake, they can be killed. It is a harsh realm, where only the powerful or intelligent and utterly secretive rule.
The uncaring entity that has created this realm feels little for the residents; it only wishes to observe their interactions. It seeks to observe what order establishes itself out of the chaos and where its weaknesses lie.
[OOC the Delve is a realm created by an outer power to observe the effects of combing the creatures of infinite realms into one area. Much in the vein of Planescape and Ravenloft.]