Ive taken a few fairly large doses of salvia, once while on shrooms. more than twice salvia has made me forget existance altogether. My mind goes completely 100% blank and I get absorbed into nothingness, into absolute nonexistance. Upon waking I usually have to remember things that I seem to have forgotten about the world while tripping, like who is around me, how to form words, how to walk, what to think about certain situations, how to hold a conversation, and so on. Once the whole experience is over (15 minutes?) I come back completely.

Very intense stuff, most of my friends are scared of it.