Remathilis
Legend
4e introduced "everything is core" as a notion. 3e had begun with "All you need is the Core 3" but gave that up come mid 3.5 (arguably PHB 2 killed and notion of it). 5e returned to the notion, but even then it's lip service as several setting books pushed PCs towards supplemental cleric domains, and additional spells were tagged as being artificer spells.I see to recall multiple books for Dark Sun and the Realms in 4e...