Realms 101
A Realm!
The next tier of the Spiritual World was not anything simple like going from a Large World and into a Prime World. Similar to the past upgrade where it went from needing the Core of a Small World to needing the Core of a Large World for the upgrade he just conducted, the next rank did not just ask for a Prime World Core, but 5 of them in order to take the Spiritual World into the stage of a Realm at once!
This stage was something very few Worlds were capable of achieving, there needing to be numerous qualities that had to be met before such an event could take place.
An example was something like the Ancient Blood World where the Vampyre Progenitor left behind. That enormous world had become a Realm in the past, but it had downgraded over time and returned to a Prime World as nearly all of its people were gone from it, the essence and status of the world gradually declining until it returned to a Prime one.