I have rolled a probably a couple hundred times over the last 15 years. Always been good. Now for the first time I was snorting a decent amount of coke in the morning, and later in the afternoon we took our MDMA. My friend fired off within about 20 minutes or so meanwhile i was sitting there with literally nothing happening. Within an hour my friend was rolling and I was left there just feeling a bit annoyed because somehow his MDMA was real and mine must have been fake, although it came from the same source. So anyway, I have read a few other reports that coke can block MDMA and I can tell you this is 100% true. It totally and completely blocks any effects at all, it doesn't just lower the effects or reduce it. Total termination of the whole roll. All i gotta say is wow.