to replicate: build caster character at level 20, select Lv 10 spell, reduce class to Lv 13 → selected lv 10 spell still appears in spellbook and on character sheet.
to replicate: build caster character at level 20, select Lv 10 spell, reduce class to Lv 13 → selected lv 10 spell still appears in spellbook and on character sheet.