Right sorry it took a while, but here's what happened:
Supposedly 1mg blotters came in the post (same size as acid sized blotters). I have no way of verifying the substance or the quantity, but for the sake of argument it was 1mg of 25B - NBOMe.
2 people ingested it, myself and another. Held 1 each under our tongues for quite some time til it all fell to bits, had a strong chemical taste akin to acid. First thing that became apparent was a blatant stimulant feeling maybe 20 minutes in strong enough to utterly nullify all the alcohol we'd been drinking.
About 40 minutes in a definite tryptamine headspace kinda feeling started developing, at this point was quite clear something rather intense was going on. Was quite some time for visuals to develop properly maybe about the 1.5-2 hour mark (hard to say). Stimulant feeling by this point (vasoconstriction and generally vibrating!) was getting rather strong bordering on a little overwhelming.
Important to note at this point the bodyload was akin to oral AMT, bit unpleasant.
A major theme of the whole experience for both of us was the illusion of being underwater. Looking out the window/inside the flat everything was just so clearly underwater! I as well as everything else was bobbing and floating with the current. My partner was convinced she was drowning during the first 2-3 hours which worried me for quite some time til we ascertained it was probably psychological.
Closed eye was incredibly strong some of the most complex fractals I've ever seen made out of bits of squid and manta rays and later on generally anything else in the room (eyes open or closed). Quite a lot of luminous flashy stuff going on.
Whole experience from kicking in to just remaining after effects was easily 9-10 hours. Sleep was pretty much impossible until about 6 hours after this.
Comedy moment: "my nose is flashing look look LOOK! my nose is flashing!"
"That's your cigarette..."
Have been pretty strung out since the experience (is somewhere between 48 and 72 hours later now), had an utterly fried head even after an initial 10 hours sleep for the entire of the next day pretty much just able to answer things to a complexity of "yes" or "no".
Sleep has been incredibly vivid, a la sleep paralysis ever since.
I believe the probably rather fantastic hangover that was going on under the surface (totally disguised by the stim effects of this substance) could have been largely responsible for: heavy vasoconstriction, v. strained cardiac feeling, headaches and a few others that at times felt like they could have got v. serious v.fast.
I got the feeling maybe 1mg was too much, but I can't say for sure based on the above paragraph^^ I may have induced my own discomfort to an unknown degree. Other person present reported similar, but had also been drinking heavily.
All in all I'm totally unsure what to make of this. Was a hell of a ride I'm still feeling now!
EDIT: Totally forgot to mention, although the visuals were v. strong I felt as if the complexity of acid was missing from the thought patterns. Not really sure I learned anything, but I saw some amazing things!
Also note: I have not taken any tryptamines in a couple of weeks, I shouldn't have any tolerance