Illusion & Enchanting

[baldurs_gate_2]

So it's not possible to get the +3 Bonus from Spirit Shield and the +5 Bonus from Iron Skin together? And the same with Wizards Double and Mirror Image.

[Loren Tyr]

No, active effects (stuff from activated abilities including modals, spells, scrolls, potions, etc.) don't stack with each other. The highest bonus counts (and the highest penalty). 

 

It's not always entirely intuitive though, sometimes you do get stack anyway. This applies I think to all "probability for X to happen" stuff, so eg. two 20% hit-to-crit chance bonuses from active effects would stack (to a combined 36%, rather than 40%), and similar with for example "X% chance to interrupt on hit" effects. Similar but different effects also stack: the "+20 deflection against melee" from quarterstaff modal does stack (against melee attacks) with general "+X deflection" from other active sources.