Insanity too. And idk how BG worked with this, but P:Km has this nice mechanic where casting a targeted spell on an insane party member who has mirror image up can hit one of the images! And you need Heal or better (6th+ level spells) to cure insanity, which my party did not have many uses of.
That was a fun "cast Heal -> hit mirror image -> my insane party member kills another party member -> no more level 6 spell slots so reload -> repeat"
