I picked up a free sample of the Level 2 China White on TR (they are also on Dream) and it blew my mind. I have a pretty high tolerance for most drugs (unfortunately) but this knocked me on my ass.
I smoked the tiniest bit at a time and Jesus, I was nodding so hard I practically passed out in the bathroom after a couple of hits. But in a good way.
The best part of their heroin was that unlike the vaaast majority I have tried this had virtually no taste whatsoever when smoking it. I get gaggy so I hate it when shit tastes bad. It burned super clean too so that was pretty cool as well.
They also have synthetic heroin but I don't know what that means so I just went with the China White.
The levels though. There are 5 levels and cdnven has a guide on their profile page that should help you determine which is right for you. It depends on things like if you do fent, heroin or something like codeine regularly.
ONE THING: Please start out with a small dose, this shit is pretty powerful.
It is Fent that's why so strong.