If you take it before you roll, you probably won't roll...Take it when you're coming down or soon after you're down, I doubt it's been proven that it protects from all damage, but it has been shown to help lower neurotoxicity.
Prozac after the roll has been said to act as a nueroprotectant.
Ive nabbed this from mdma.net (RGB would have simply known it)
Post-E Prozac in particular mitigates the oxidative stress and consequent risk of serotonergic axon damage caused by reactive products of dopamine deamination. The long-acting SSRI Prozac/fluoxetine, and its even longer-acting metabolite norfluoxetine, apparently prevents the uptake of dopamine (and any toxic metabolite(s)?) into the serotonergic nerve terminals by binding to the serotonin reuptake transporter with higher affinity than MDMA or serotonin.