It is a fearless giant lion, keeping bunny kingdom safe and guards near the path that leads to king's castle. He is next after Giant Lizard by level and location.
After defeating the boss, you receive a Blue Chest as a reward. Lion Guardian may be defeated only once per timeline.
After defeating the Lion Guardian for the first time, you will receive the achievement "Clear Area X" which multiplies non-tap monsters' DPS by 1.02.