I give my vote to Salvia. If you want to shatter your sense of self and feel like your body is all tied up in knots, it could get dark in a jiffy. I had tons of that shit and threw it all away. I love psychedelics, and I get that if done just right, Salvia can be an adventure, but what I experienced on it was not for me. If I am going for breakthrough experiences, I'll go straight for the n,n,DMT, smoked. Also, I recall having some weird times on 3-meo-pcp. It might be considered dark, but so am I, and perhaps I did a little too much over time and was glad when it was gone. That shit's no joke...