My tentative conclusion, based exclusively on eating rolls, is that the message about primordial seas you get when you eat sushi with Ocean Sight active adds three energy to what you'd otherwise get from eating the sushi. It could be a percentage increase, though. It might also give a bonus equal to the food's hunger requirement, in which case we'd expect +1 adventures from sashimi and +2 adventures from sushi. Giant puffballs give 18-20 energy for 9 hunger. Anybody want to eat one with Fae Sight active and see if they get 27-29 energy?
Sushi / Discussion