Endurance potions permanently decrease the amount of stamina taken per step. It's not very noticeable unless you've had some speed potions, but flying around the island will drain your stamina fast, and endurance potions will let you go a lot farther before needing to eat. Endurance potions don't decrease stamina costs of actions and overweight penalties though.
 "IntoSpace!"){kind=icon}
 "Crush Crush"){kind=icon}
 "Aground"){kind=icon}
 "Pillage the Village"){kind=icon}
 "Slurpy Derpy"){kind=icon}
 "Burrito Bison: Launcha Libre"){kind=icon}
 "Crafting Idle Clicker"){kind=icon}
 "The Journey Home"){kind=icon}
 "Mutilate-a-Doll 2"){kind=icon}
Endurance potions permanently decrease the amount of stamina taken per step. It's not very noticeable unless you've had some speed potions, but flying around the island will drain your stamina fast, and endurance potions will let you go a lot farther before needing to eat. Endurance potions don't decrease stamina costs of actions and overweight penalties though.