Open the entrance of the Vault of Defiled Truth inside the Duskmoon Tower. Each time you run into Barrock, purchase three Rancid Bait Meat. Defeat all enemies in Duskmoon Tower courtyard and stand next to the entrance of Vault of Defiled Truth. Use the Rancid Bait Meat. Cursed Dragon should appear. If not, enter the Vault and exit back into Duskmoon Tower courtyard, and the dragon will be there. Defeat the dragon, collect the items, and Rift Crystals. As long as Rancid Bait Meat is there, enter Vault, exit, and the dragon will re-appear. Drop more Rancid Bait Meat and repeat the process.