There isn't really a clean way to remove that bonus spell. The built-in spell adjustment for Fox's Cunning causes the same error.

The underlying mechanism that tracks and applies bonuses doesn't distinguish between temporary and permanent bonuses, so there isn't any way to tell how much of the current attribute is temporary or permanent when the built-in class script determines how many bonus spellbook spells should be added.

It should be possible to code the item to subtract a bonus spellbook spell, but it would do the wrong thing if another alchemical bonus was also affecting Intelligence, and it would have to be written to specifically handle each class that has some sort of ability-based bonus that shouldn't be affected (another example would be the extra starting Alchemist formulas gained).

And please report the bug - there's two sub-totals on each ability score - the permanent modifiers that can change languages, bonus spells, etc. and the temporary modifiers that shouldn't affect those values. We've either got a bug where the alchemical bonus is being put into the permanent sub-total, or a bug where the spellbook spells are looking at the final total, not the permanent sub-total.

Mathias, as far as I can tell there isn't a division between permanent and temporary; it's separated by bonus type for the ability scores to determine what goes into the aNormal/aBonus and aFinalVal/aModBonus versions of the attribute.

I think the scripts for bonus spell book spells / alchemist formulas / etc are working off the aFinalVal/aModBonus values because enhancement bonuses can be permanent or temporary depending on the source, and enhancement bonuses aren't included in the aNormal/aBonus attribute values.

For example, ability score boosting items like the headband of vast intelligence or the belt of giant strength have enhancement bonuses which should be treated as permanent bonuses after the first 24 hours, with the added hiccup that the intelligence items still aren't supposed to affect skill points (since the items grant ranks in a particular skill instead).

The enhancement bonus from ability boosting spells like Fox's Cunning should be temporary, but there isn't a way to tell hero lab whether the enhancement bonus is a temporary enhancement bonus or a permanent one.

If the bonus wizard spell book / alchemist formula scripts are modified to use the current aNormal/aBonus they won't have the correct values when there is a permanent enhancement bonus from a stat-boosting item, and if all enhancement bonuses are added into aNormal/aBonus then we will still have a different error when there is a temporary enhancement bonus from a spell/etc.


(The number of languages known is an example of something that seems to use aNormal/aBonus instead of aFinalValue/aModBonus, and the stat-boosting items which raise intelligence have to manually increase the number of languages known. But using that approach for other things would require the script for those items to manually increase the wizard spell book spells and alchemist formulas too -- and probably more things which I don't know about off the top of my head -- and breaks in the case where a hero is wearing multiple items which grant a permanent enhancement bonus to intelligence since the manual adjustments "stack" even though the bonuses shouldn't.)