Another question

If a unit has 2 spellbooks of the same type, is it possible to identify the one you used?

I'm pretty sure no, since using the same spellbook spell on the same unit screws up when you're casting a spell anyway (same id).

forgot to mention im using item with spellbook ability
so i wanna know which item casted

GetManipulatedItem()

try it with a spellbook

Does that detect item abilities? As far as I know, you use the caster event to catch item usage.

It works with EVENT_PLAYER_UNIT_USE_ITEM and few other item related things.
But i am using an item with spellbook ability which does not work with USE_ITEM
The detection of the usage is by the spellbooks spells with EVENT_PLAYER_UNIT_SPELL_EFFECT

so does anyone know a way to get the casting item?