This article's content is accurate to the most recent public game version, 0.4.8d.
"You have a very bad feeling about this bottle..."
The Poison Bottle is an item that, when used, defeats the party instantly. Only one use of the item is required in a battle, as it affects every party member by dealing an unblockable 9999 damage each. While technically a consumable item, it can be used an unlimited number of times.
Unlike any other item in the game, the Poison Bottle is given to the player right at the start. It is also stated to be non-canonical and therefore receives no acknowledgement by the story or its characters in any way.