It is quite straightforward, increasing max HP with no secondary effect. Its effect is stackable, and can be used to add additional bulk to an ally.
How to Acquire
Found in the Snakemouth Depths, one room after saving Leif, on a pillar in the middle of the room.
Found hidden behind a waterfall, in front of the bridge to the Lost Sands. It is out of sight, and can only be retrieved by throwing the Beemerang at it. The outskirts are unlocked after Chapter 2 begins.
When Chapter 3 starts, this medal can be bought from Shades in the Underground Tavern for 2 crystal berries.