As in the move 'Gift Boxes' from Fnaf World.
It could work much like totems of undying, where if you die while holding the item, it'll prevent you from dying and restore your health
Maybe it could be dropped from bosses or found in structures. The item could have a yellow glow or something similar to differentiate it from regular presents.
Alternatively it could be a status effect
After drinking a potion or defeating a boss, it'll give you the Giftboxes effect, The effect lasts infinitely until the player dies, then it'll activate. Making it an effect prevents players from stock up 20 giftboxes and never dying like totems of undying.
Gift Boxes is an essential move in Fnaf World to beating the game, more than any bytes or upgrades. So I think it deserves an inclusion and it would fit well into the survival aspect of the mod