After you go through the Dark Rift you will be able to go back. 
After you finish off all the tasks and you have to go around 
the world, go back to the Dark Rift and go to the exit. 
You will see a large black Elooper which is stronger than 
Ramirez. Get into battle with it and automatically use Vyse's 
Skull Shield, Aika's Blocking Magic special, Drachma's Spirit 
Charge, and have Fina Focus. Repeat until you get the Prophecy 
crew special and use it. Keep doing this until it dies to get 
7000 experience points.