I’m not exactly sure.
I believe he's talking about mixing essential oils like asarone, eugenol, elemicin, safrole, myristicin, with active phenethylamines to potentiate their effects. Mescaline is a phenethylamine.
I have read elsewhere that sassafras potentiates san pedro quite a bit, or san pedro potentiates sassafras (depending on how you look at it).
But maybe he’s talking about mixing them with phenethylamine specifically to cause them to form phenethylamines in the body? There’s been some theories about that being possible, but nothing’s been proven. The idea was that by supplementing the body with phenethylamine, that the theoretical conversion from myristicin to MMDA in the body would be more likely to happen. And that this was the reason some people got good effects from nutmeg while others did not, it all had to do with dietary phenethylamine intake.
You can buy pure phenethylamine at many herb and nutrition stores. If the proposed theory works, you should be able to take a small dose of nutmeg, and a good dose of phenethylamine, and it should cause the body to make MMDA from the two.
I don’t know enough about the metabolism of these compounds to have any idea of how realistic or ridiculous that theory might be.
But mixing these oils with things like MDMA and mescaline has generally given very positive results where the compound’s potency was increased. This seems to be real. There are plenty of trip reports showing that happens. But that is drug "synergy" at play.