From the Super Mario Wiki
Mario using a
Red Essence.
A
Red Essence is a drink in a red-colored soda cup in
Super Mario RPG: Legend of the Seven Stars that, when used in battle, makes the character (
Mario,
Mallow,
Geno,
Bowser, or
Toadstool) invincible for at least three turns. Rarely, a Red Essence will last for up to five turns, and the player may also be able to get a
freebie. This may come in handy when fighting tough bosses, such as
Jinx or
Smithy. The Red Essence is available in the Inn in
Nimbus Land given by
Toad after Mario wakes up from a nightmare, and there is a hidden one in the Forest Maze near the save point.
