Ha, I had just found my old copy (first edition but raggedy) of The Essential Psychedelic Guide by DMT Turner. That guy (RIP) had info on a whole lot of combos. I just read this same thing but his was about ketamine. Here is from the book:
When one takes a natural psychedelic like mescaline, they often come into contact with age old entities of that realm. With mescaline I find I become that branch of a living entity, often called Mescalito, who has existed since humans first ingested psychoactive cacti. . Mescalito can be viewed as being the conglomeration of experiences of all mescaline users. It feels as though when I take mescaline I am the "eye" of mescalito, and that he experiences through me. Mescaline has experienced much during his 3000+ year lifetime. However, my introducing him to a powerful synthetic anesthetic/psychedelic left him shocked, stunned and confused. It was as serious insult on my part to force this experience on Mescalito, especially since omens were telling me not to do it.
It seems as though the "entities of the natural psychedelic realms are adverse to having their realms polluted by people combining them with K. I also feel these entities frown upon excessive or indiscriminate use of K by itself.
We have to keep in mind this was in the early 1990's. Ketamine was not popular. Terrence McKenna talks of a large empty room when he tried it which is what I got in 1990 after 15 tries. Used a few vials of Ketaset IM over that summer. But now that it has existed it is possible that a morphic resonance has occurred in the last 30 years with ketamine users "filling in" that empty room with experience, much like DM Turner was attributing to mescaline. Just a thought. He said it combined nicely with LSD. So that variable makes me think I am wrong.
But if tryptakid states the same in 2025, then maybe it has nothing to do with morphic resonance. I have to keep in mind DM Turner said he got addicted to ketamine and DMT along with mushrooms helped him back away.