Fentanyl is also garbage that looms in the darkness to bring the zombies.
High lasts 2 hours or so, versus much longer for heroin. The withdrawals are also more intense.
It is a one-dimensional high as well.
The only reason I'm posting this is as heroin supplies dwindle, and prescription opiates become harder to get, fentanyl will dominate and every fucked up thing about opiate addiction will amplify 100 times.
Once addictions are imprinted, people act 100% according to behaviorist predictions. Easy to control, easy to manipulate, easy to unleash upon "regular" people to cause chaos.