I've had two, very interesting, and very different experiences with this...
On one occasion, I had an oral Syrian Rue and DMT extract trip, and it was quite low key and subtle, so i thought I would smoke some spice, to spice it up a bit.
The pipe was less than ideal, and I was fumbling around in the darkness with a bit of a crappy lighter, so I wasn't expecting too much...
However I managed to take a few decent tokes, and was suddenly launched into a realm of pure bliss and light. There were beautiful, and highly ordered geometric patterns...they seemed to mean something...like a kind of pure, visual language, which I was unable to translate however...the feeling was one of compete calmness, and being bathed in a beautiful golden light...in fact that has to rate as one of my most awesome DMT experiences. The trip was prolonged and integrated, and felt very different to a 'sober' DMT trip.
However, the next occasion was an intergalactic ass whooping...
Myself and my good friend had again taken some Syrian Rue and DMT, but it was again subtle and low key, we both had a nice buzz, but that was about it. So we decided to smoke some spice...
I went first, and I think we may have been a bit over zealous with the spice...my friend estimated it as being around 100mg. He applied the lighter, encouraged me to take more (including the third toke, Terrence McKenna style), and he took the pipe from me.
Well after the first toke, looking down the pipe at my smiling friend and my room, the room was already severely altered...perhaps more than ever before. At my friends advice I get toking....ad then WHAM...
Right before I went, there was this curious rippling in the room in front of me, like reality is a liquid...the only time I've had this before was a caapi/DMT/mushroom trip (also very intense)
What very rapidly engulfed my brain is without a shadow of a doubt the few most terrifying minutes of my life. I've been in a near plane crash, and poisoned myself with Iboga, but these simply did not compare to these few minutes.. Absolute, toe curling, pure, unrelenting terror. It was mental torture, the mind was being overloaded with FAR more energy than it was designed to handle.
The visions were extremely menacing and alien...the experience felt very threatening, literally like I could be abducted by fuck knows what at any time. Imagine being plunged into a completely parallel dimension, some kind of quantum dimension, where different rules govern it, and you have no idea how to navigate it, there is too much chaos and energy to handle. The brain is overloaded, and your primitive brain circuits, the 'flight and fight' circuit has been activated...only you are powerless to do either...
Naturally I was a little shaken for a while, but I still feel it was special glimpse into somewhere else. If there is alien life out there, I think we are much more likely to encounter it in parallel dimensions...bath far and near, rather than contacting it many hundreds of light years away. I also got the feeling that there might be something out there, or everywhere, some sort of universal power or architect...I dunno though.
Definitely one of my weirdest and scariest experinces...