I'm playing IWD2 Classic with mods having started the game way back when. The last mod I installed then was to replace most of the goblins in the Prologue (Targus) with skeletons. I find this punishingly difficult, or else I've just lost my grasp of tactics in this game.

I started one character as a halfling rogue (the second halfling on the menu), which has preferred class Rogue (the third one does not). Since I have 18 INT I thought I could multiclass to Wizard / Mage and have access to spells - but after levelling up from Rogue to Wizard there is no icon with crescent moon and stars (see attached screenshot with the rogue/wizard selected). My single class Clerics and Sorceror all have the icon, and can cast fine.

I tried resting and then learning and memorising minor mirror image. No difference. Only the rogue skills appear.

What am I doing wrong?

Thanks! I had completely forgotten this