When you say pills, pills of what?
Amphetamine + Ketamine has a peculiar empathogenic bent that I've never heard other people speak on, I'm glad to hear it brought up here. Benzos and amphetamines (or other uppers) can also be beautiful but if pushed too far can lead to some very bullshit antics, my favorite combo of them was ketamine, MDPM (methylenedioxyphenylmorpholine) and etizolam put together. I was using ketamine daily (as well as cannabis) at that time so it was more of a maintenance thing than anything else, and MDPM is a really just a stimulant despite the methylenedioxy moiety. MDPM is sort of what phenidates wish they were, and combining it with etizolam led to a state of perfectly peaceful, focused, energized cognition that had me writing code like a machine. Flualprazolam (or other triazolobenzodiazepines specifically) alongside any stimulant also is a great combo for sex that I rarely hear mentioned.
I often find combinations reduce side effects for me, interesting. I've mixed GHB and a kratom extract shot before and it was absolute bliss, but in college before I knew anything at all about harm reduction I used to find the alprazolam, kratom, alcohol, GHB, and cannabis five-way combination profoundly euphoric. Any two of the three GABAergics mentioned there though (GHB, benzos and/or alcohol) could be easily fatal, I think I only pulled through because of luck and the fact that I was a 225 powerlifter who was using GHB often enough to have a slight tolerance, as it's an HGH secretagogue and was easier than normal HGH administration. I just want to reiterate again, do not mix those drugs I just mentioned, I am VERY lucky to still be alive after doing that stupid shit.