Its weird actually, I've added a little pinch of Salvia leaves to some changa, and it worked very nicely indeed, and completely altered the experience. Myself and my friend experienced an amazing sense of peace after smoking it...one was so blissful, and completely enveloped in the sensation of existing of the here and now, that one had no desire to move or talk during the experience. The night before we had drunk some caapi (and chaliponga) that had only produced threshold effects, so I'm not sure if this was still in our systems having an influence. The experience lasted a decent amount of time, and there was a pleasant afterglow for some time afterwards. Salvia changa has been called 'changra' by my friends....the effects resemble psychedelic opium.
However, one other time, not having experienced a Salvia journey for a very long time, I attempted smoking some 40x extract in a bong. Unfortunately, I noobed this up, smokign during the day, as oppose to a dark, quiet room.
I felt altered in a weird way I couldn't really pinpoint, and 10 mins later, I thought I would salvage a trip by smoking some spice...
BIG mistake...got the 'ferocious, unrelenting terror' vibe, similar to when I smoked far too much DMT while on Syrian Rue. The universe immediately began to mutate and the 'flight and fight' part of my brain was zapped on. Not fun but didn't last long. This was completely my fault though not showing the repect that these extremely powerful things deserve.
A weird note on the Salvia flashback front...once when coming down off a mushroom trip, I had a little pipe of good cannabis...and WHAMMO...I was launched into Salvia space...was really weird and very vivid, and not friendly...mainly because I wasn't expecting it at all. But I was getting all those uniquely weird effects that are part of Salvia's territory. Only experience like this I've ever had.