This stage might be cycled around like the other awakening stages (no confirmation for now).
The battle starts with Those Guys and Hippoe being spawned from the enemy base, it'll continue for a bit. When the enemy base HP goes down to range near 98303-98920, Value Meal Cat (enemy) will appear with a boss shockwave, accompanied by Kang Roo. Then the enemy base will continuously spawn Kang Roos accompanied by Hippoes and Those Guys. Be careful because these enemies are buffed to extremely high percentages but they are easy to deal with if you have good meatshielding, it will just take time, we are not sure why it is marked merciless due to its difficulty but we think its because of the buffs
The stage is pretty straightforward, just send a wall of Wall Cats to stall the enemy or spam a lot of heavy hitters like Paris Cat to finish the stage quickly. Even the boss isn't that much of a threat.