The place I found great to lvl in this chapter is located far to the left of where you first enter. There are yellow and blue imps here, and there's a group of 5 blue ones near the edge of the cliff. Get a party of Lightning as a Com, player controlled, then Hope as a syn, then Snow as a sen. Then, as soon as the battle starts, use blitz on the D enemy, because it's the most in the middle, and will give the highest chance of hitting all the enemies every time. If you've killed one of these imps before, then Hope should have given you enfrost or enwater already, so you should be hitting them all pretty hard, and with the sen provoking right away(I swear it's a 100% chance) they will have a debuff, so 2 blitzes will charge 2 atb gauges from the skill that causes you to regain atb from attacking things with debuffs, and just keep repeating. If underleveled, the fight is about 24 seconds each, but near the end it's about 12 each. 3700 CP each fight, too. To respawn it, go to the treasure chest by where the 1 yellow and 2 blue imps spawn. I did this for a while and got all 3 main cryses mastered with all chars.