I have a vial of Posion how do I use it? Also Belsorigs(sp) poison can you use that in anyway besides for the water temple quest?
AFAIK, there isn't any use for the vials of poison you find, unless it's to harm your characters if you use them w/o identifying them first, since they're listed as 'magic potions'. If your appraise skill is high enough though they can be sold at a decent profit.
I've never tried it with poison, but when I've attempted to administer potions to charmed PCs in combat I've noticed that it's opposed by some sort of dice roll, so perhaps (unrealistic as it sounds) you can use it against enemies in combat..
if you've identified it, you can use and see it at the: inventory radial menu> potions > poison. iirc
It should be a grenade weapon and make a poisonous cloud, all be it a small one. This IS just my opinion of course.
