Benzos (or alcohol) + LSD has been done to death in this thread and elsewhere on the forum. Myself and some others are strongly opposed to it on the grounds that it dulls the trip and anything you get out of it, spiritually/personal growth wise, or whatever, and reduces it to some confused, muddled eye candy (if you want eye candy, there are winamp plugins for that). Some people disagree. If you have problems with panic attacks and the like, by all means, keep a quick-acting benzo on hand if you start to freak out, but you will usually find that by exercising some mental discipline you can snap yourself out of panic on acid, or at the very least keep your composure and avoid doing anything stupid. Often the most anxiety producing experiences are the ones that we learn the most from. Would you want to deprive yourself of that? Please don't combine LSD with downers of any sort.