It drops from BCNM Treasures and Tribulations... but I suck at eenie meenie miney moe... I know! We'll make an event out of it and kill that treasure chest! Note to me: I still owe Belli one of those rings.
I've got about a 50% rate of choosing the right chest. Just not anything good from it yet.
Update- Did is alot better at guessing than I am. We went 3/5 just guessing chests but yeah, nothing good dropped.
hrmmmm.
[edit] and of course while were there one popped up on the ah and was just as quickly snatched up...