The only enemy, Oldhorn, spawns 10 seconds in with a boss shockwave. Nothing else spawns for the remainder of the battle.
All you need is a way to deal with this one, strong enemy. Cat Jobs (any form), Sniper the Deadeye (true form), talented Doctor Cat, Kubilan Pasalan (only evolved form), Healer and few other units can completely trivialize this stage, so they should be used if owned. Besides them, there are plenty of cats that can also make a huge difference if used, such as Ururun, Modern, Thaumaturge (do not use if using Cat Jobs), Delinquent Cat (true form), talented Rodeo, talented Vars and others.
If you use knockback units, bring as many of them as possible alongside some meatshields, also bring knockback up combos and, if using Doctor, some research up combos too. Oldhorn will just be unable to progress and eventually die.
If relying on freeze, slow or weaken, bring many meatshields and as many units with all three of these abilities as you can, while avoiding the less effective options. Wait for Oldhorn to advance a little, then stop him with meatshields, then your units, while saving Healer, if using him, for last. Oldhorn should easily get stuck unable to advance and will quickly fall.
- This stage has a max enemy limit of 15 despite only having one enemy.