place: Den of Crowmen - hardmode
Start hard mode
kite the big bird while you are killing the small one
when the small one is close to 10% (when he is about to turn to unattackble), chain stun/fear him and kill him while CCd. This will end up in epic loot. Then reset the big boss. It will this way take around 5-10 minutes per rare token. Also the AA xp will be insane.
YOU WILL NOT GET INSTANCE COOLDOWN IF YOU DONT KILL THE BIG BIRD