A spell is a one-time magical effect that come in two types: arcane (cast by bards, sorcerers, and wizards) and divine (cast by clerics, druids, and experienced paladins and rangers).
This section is mainly for changes to the base game spells: PAGE INFO ALREADY TRANSFERRED TO THE NEW WIKI - Spells Changes and new spells new, The official documentation for the base game spells is here: https://nwn.fandom.com/wiki/Category:Spells