Hello!
For a month already it doesn't work: Killing the boss does not count.
We thought that its a summoner and:
were waiting for up to 20 min (thats insane)
were hitiing it until 50% HP (as rumor say)
I think it's simply BUGGED!!!
Please take this post numb. 507 on this issue into consideration and work over this ASAP
Many thx!