Weeping Dunes is the third stage in Kombu Cape.
Henry will stop most of your units, so bring fast attackers such as Manic Lion and Maglev. Try to get the H. Nahs to stack in front of the enemies and call in Awakened Bahamut to attack them all at once. The rest is just timing: Once Henry attacks a cat, the cat will suffer a slow and painful death. Unless of course the Henry dies first. Note: The frozen cats still count in the total cats (obviously) but Henry has low attack power, so you will reach your cat limit easily, making timing more difficult. Not that meatshields matter that much here: it is difficult to slip through the Henrys. Bring along Manic Eraser and Manic Mohawk as they are faster and can slip through much easier.
Alternatively, you can cheese the stage using Maglev, Manic Lion, and Awakened Bahamut.