How Exactly Does This Work?

I tried eating it when I was missing 29 Will points from potions, and I went down to missing only 16 Will from max (+13).

So Idunno' where the 4 came from or what it actually is, I don't have enough to test and I don't feel like cooking and chugging for an hour when somebody can go sit in the hot springs for 10 seconds to remove all potion poisoning anyways.

It would be good if you're doing something hard and long like Rabbie Phantasm and get pot poisoned there. You could make a few pets' inventory full of these and try to counteract the pot poison. How many points of pot poison it removes, that I don't know