Thread:Lostone2/@comment-27713488-20160206050445/@comment-27384637-20160208055537

He's pointing out the difference between the noun "incubi" and the proper noun "Incubus", because "Incubus Kings" is a proper noun it doesn't need to be pluralized into "Incubi" and can stay (and often reads better) as "Incubus". Basically it's semantics.