It sounds like that are simply letting caster levels stack for the purpose of Learning/Preparing spells as well as number of spell slots. PnP rules are a bit woolly on that topic anyway.

As per PnP rules, it's possible for a multiclassed character to have a 3rd level spell slot, but not know any 3rd level spells to cast with it.

Last edited by FrostyFardragon; 11/07/23 07:55 AM.