From Guild Wars 2 Wiki
— In-game description
- Two earned from the Glorious Chest after defeating each zone's boss (once per day per zone).
- Four earned from each World 2 zone done in Tribulation Mode. (once per day, per zone)
- One earned after completing either Bonus round (Cart or Robbers, also once per day).
- The name is a reference to Bubble Bobble.