[RPG] What happens when a Wizard loses Intelligence after preparing his spells

ability-scoresdnd-5espellcastingspellswizard

A Wizard prepares a number of spells equal to his Wizard level + his Intelligence modifier.

But what happens if he loses Intelligence (the most obvious way I can think of is unattuning to a Headband of intellect and having a base Intelligence score of less than 18) after preparing his spells? Does he…

  1. Lose access to the first [INT mod lost] spells he prepared?
  2. Lose access to the last [INT mod lost] spells he prepared?
  3. Randomly lose access to [INT mod lost] of the spells he prepared?
  4. Keep access to all his prepared spells (but will be able to prepare fewer spells after his next long rest, unless he regains the lost intelligence)?

Best Answer

Losing intelligence probably shouldn't affect the Wizard's currently prepared spells

Ability score loss/damage is an uncommon mechanic in 5e and there are no general rules about how it works. However, it looks like losing intelligence shouldn't affect the wizard's access to currently prepared spells. Excerpting from the Wizard's class description:

You prepare the list of wizard spells that are available for you to cast. To do so, choose a number of wizard spells from your spellbook equal to your Intelligence modifier + your wizard level (minimum of one spell).

[...]

You can change your list of prepared spells when you finish a long rest. Preparing a new list of wizard spells requires time spent studying your spellbook and memorizing the incantations and gestures you must make to cast the spell: at least 1 minute per spell level for each spell on your list.

No circumstances are given for the Wizard's spell list changing except for if they change their list of prepared spells when finishing a long rest. I would interpret these rules to mean that the precise value of the Wizard's intelligence is only relevant at the moment they are preparing a list of spells; their intelligence, and their wizarding skill (as represented by their level) determines how efficiently they're able to prepare their spell list, but once it is prepared, that's it - the list is fixed until they change it.

I'd further argue that preparing a new list of spells is an entirely optional part of the day for the Wizard; nothing states that taking a long rest causes them to forget their current list, only that they can memorize a new list instead after they've taken a rest. If the Wizard chooses not to prepare a new spell list, I would rule that they retain access to all the spells they already had prepared, even if their intelligence has changed.