[q=CB!'s guide]** It is impossible to defeat the Magic Urn using physical attacks, despite it having a finite HP statistic. Even when attacking it, if a member of your party is equipped with a weapon bearing [Sensor], you'll see that its HP does not decrease. The Magic Urn is succeptable to Zanmato, Doom, and Death Sentence, but in my opinion, all of these are a waste of gil and time due to the lack of rewards for defeating it - no AP, no gil, no shirt, no shoes, no service.

Anyway, after attacking any of the five "eyes" on it, the Magic Urn will respond with either "BINGO!" or "WRONG!". "BINGO!" is what you want to see - hitting the randomly-chosen correct spot will yield you one of the following items: Elixir, Phoenix Down, Frag Grenade, Silver Hourglass, Lunar Curtain, Soul Spring, or Stamina Tablet. "WRONG!" means you've hit the wrong spot, and the Magic Urn will then attack your entire party for big damage, then run away. A final note to veteran players - the Magic Urn does not ask for Elixirs in this game, therefore give it none. Using an item on an "eye", and attacking the "eye" have the exact same result.[/q]

If CB! says it's random, then random it is. :\