It says: "Carrying this will save you from death once but consumes all current energy." At first glance, "consumes all current energy" doesn't seem like a penalty at all, since simply going to a new room will replenish your energy. But perhaps it means: when you die, you'll come back with 0 energy. But that doesn't seem all that bad; again, just go to a new room and get your energy back. But perhaps it means: you get one recovery from death, but as soon as you equip this, you'll have no energy for the rest of the game, permanently. Or maybe it means: when you die, you'll come back, but you'll lose all energy, permanently.
It's only these last two options that seems like a reasonable, offsetting penalty for the (amazing) benefit. So which is it? The wording seems ambiguous.
Thanks.