I warmly suggest you to save before engaging battles and especially before opening temple doors that could lead to battle
Why ? Very simple:
Some spells effects could be PERMANENT ...
One of my spellcasters has been silenced during a battle and now he's useless. There's no way to unsilence him, tried everything, even resting for a month.
I had a savegame not long before but what if i didn't save for a while ?
So keep an eye for spellcasters and aim very well before casting yourself