Captain's Banquet is definitely amazing, for the other bonuses too, and should be used for any tough fight, but it's expensive and limited. Drugs for regular fights. I just find that playstyle annoying (using consumables in general - I've beaten the game on PotD without using a single consumable, just because). But that's my personal problem.
Modwyr offhand is probably the second best option, just as a anti-confusion stat stick? Caroc armor gives up speed and damage, and priest has other things to do or will run out of casts in a long fight.
By the way at high level if you have a support chanter they have a chant that gets rid of confusion as well. Modwyr is a good stat stick anyways if its lash bonuses apply to spells but I have not tested it specifically on a spellcaster.