This is a guide for the Hellgate: London mini game.
What is the mini game?
See those three symbols at the bottom right corner of your screen? "Light" all those up and you basically get a treasure drop. I've gotten legendaries, rares, and complete crap before.
How do I complete it?
You complete it when you fulfill certain conditions. Here is a breakdown of all the symbols.

Thanks to Nocktis from HG:L forums for this.
For damage types, you use a weapon that deals that kind of damage and kill an enemy. Each enemy usually makes it go down to zero until it lights up.
For Kill Creature Type, kill that kind of monster with any weapon. You can usually find the type of monster by looking for a symbol next to the monster's name.
For Loot Type, just pick up that kind of item.
For Critical Hit, you would just have to land one. This is usually the easiest for blademasters and marksman.
Any other questions or suggestion please post here thanks!