The Potion of Poison inflicts the Poison effect for 45 seconds, gradually reducing the target's health but never killing them. It is brewed by combining an Awkward Potion with a Spider Eye in a Brewing Stand. This potion is effective for weakening enemies in combat, as it lowers health over time, leaving them vulnerable to further attacks. However, it does not affect undead mobs like Zombies or Skeletons, which are immune to Poison.