The Magic Urn is practically invincible. All you can do is attack one of its five eyes and then wait to see what happens.
If You're lucky the creature will drop an item such as an Elixer, Phoenix Down, Soul Spring, Stamina Tablet, Silver Hourglass, Frag Grenade or Lunar Curtain.
However, if you're unlucky (and you are most of the time) the Magic Urn wil blow itself up. Flight might be your best option!!!