3.5 Bonus Spells and Temporary Ability Bonuses

[Story]

Is there anything in 3.5 that clarifies how temporary ability increases, decreases, bonuses, etc. affect bonus spells? I can't seem to find any rules about this.

For instance, what happens if a Wizard with a Headband of Intellect walks into an AMF? Do they lose prepared spell slots? What if they take off the headband?

[ArcturusV]

Well, it does mention if your casting stat gets lowered, you can't cast spells above your new casting stat limitation (Page 9, Player's Handbook). So there's that. If you go to 18 int, you can't cast level 9 spells, etc.

I know Owl's Wisdom (Player's Handbook page 259) also explicitly states that you do not gain bonus spells for raised Wisdom. I don't know if that's a general rule, or specific to the nature of those stat raising temp buff.

Otherwise I can't see anything directly referencing it.

[Tsriel]

Well, it does mention if your casting stat gets lowered, you can't cast spells above your new casting stat limitation (Page 9, Player's Handbook). So there's that. If you go to 18 int, you can't cast level 9 spells, etc.

I know Owl's Wisdom (Player's Handbook page 259) also explicitly states that you do not gain bonus spells for raised Wisdom. I don't know if that's a general rule, or specific to the nature of those stat raising temp buff.

Otherwise I can't see anything directly referencing it.

Further adding to this, your allotted spells per day (including bonus spells) is all based of your core (un-enhanced) key stat. Enhancement bonuses don't give bonus spells slots, but do increase the DC to overcome the spell.

...At least, that's how I've run it over the years. It'd be a complete pain in the ass otherwise to constantly have to update and account for it.

[mattie_p]

I'd suggest treating it as a touch of idiocy (http://www.d20srd.org/srd/spells/touchOfIdiocy.htm) (walking into an AMF).

Removing the headband altogether is similar, except lose any extra granted spell slots (at the choice of the wizard).

[Krobar]

Further adding to this, your allotted spells per day (including bonus spells) is all based of your core (un-enhanced) key stat. Enhancement bonuses don't give bonus spells slots, but do increase the DC to overcome the spell.

...At least, that's how I've run it over the years. It'd be a complete pain in the ass otherwise to constantly have to update and account for it.

That's how we've run it over the years, too.

[urandom]

I think that by raw anything that increases your wisdom increases your bonus spells per day, when you prepare them. The bonus spells per day only refers to your modifier. Of course owl's wisdom doesn't apply to this because it has a specific exception. A item of +4 wisdom however would apply. I could see an argument that if you prepare bonus spells from a high ability score, and later that ability score goes down you should lose access to those bonus spells - but that seems more RAI than RAW.

[Story]

I think I'll just go with using my Int bonus at the time I prepared spells in the morning. Hopefully the issue won't come up.

[ZamielVanWeber]

Without any explicit rulings, they would work like bonus hit points. When you prepare spells you would get the bonus spells, but if you lose the bonus you need to give up spent spells. (If you get 1 bonus 3rd level spell, bringing you to 3, cast 2, then lose the bonus, you lose that last spell).

[mattie_p]

From the FAQ, p61:


Do ability enhancing items (such as the headband of
intellect, cloak of charisma, and periapt of wisdom) grant
bonus spells to the appropriate spellcasters? The spells
these items are based on would seem to prohibit it, but the
only things specifically addressed in the item descriptions
are skill points.

Yes, you can get extra bonus spells if you have an item that
increases the ability score that governs your spellcasting. To
get the extra bonus spells, you must wear the item while resting
to regain spells and all through your initial daily preparations
for spellcasting. (Even characters who don’t prepare spells need
to meditate a little while at the beginning of the day; see Daily
Readying of spells under the Sorcerers and bards section of
Chapter 10 in the PH.)
If you lose the item, you immediately lose the bonus spell
slots the item gave you, starting with any uncast spells you
have of the appropriate levels.

[Curmudgeon]

Further adding to this, your allotted spells per day (including bonus spells) is all based of your core (un-enhanced) key stat.
Huh? No, that's not right. For instance:
To prepare or cast a spell, a cleric must have a Wisdom score equal to at least 10 + the spell level. The Difficulty Class for a saving throw against a cleric’s spell is 10 + the spell level + the cleric’s Wisdom modifier.

Like other spellcasters, a cleric can cast only a certain number of spells of each spell level per day. His base daily spell allotment is given on Table: The Cleric. In addition, he receives bonus spells per day if he has a high Wisdom score. There's no "core" or "un-enhanced" anywhere in there; it's just the Wisdom score. As ArcturusV noted, Owl's Wisdom has an explicit restriction with its Wisdom boost, but that's not a general rule. You use your Wisdom score — with all unrestricted bonuses and penalties included — to determine your Cleric's daily bonus spells. Same thing for a Wizard and Intelligence; there's no restriction on bonus spells in the Headband of Intellect item description.

[Douglas]

Any bonus that lasts long enough and does not specifically state otherwise does, in fact, give bonus spell slots. Just about everything else in the game uses total ability score including all bonuses, and bonus spell slots are no exception to that. This is clear RAW.

Exactly how to handle what happens when you lose a bonus after preparing spells is a bit less clear. Immediately losing the extra slots and not getting them back until the next day (assuming the bonus is restored by then) is one way to do it. Personally I'd go with something I think is closer to the behavior of per day abilities like Turn Undead - the player chooses an appropriate set of not yet used slots to lose temporarily, but those slots are only designated as temporarily unusable, not lost and cleared; if the bonus is restored later, those slots come back complete with anything prepared in them, and they can be used immediately.