Merciless Onslaught is the 3rd stage in Axis of Evil.
This stage starts off with three relatively buffed One Horns. However, once you kill one of the One Horns, a 4000% Assassin Bear will come out as the boss. You might as well just give up right there, since it's set as the boss, so it knocks your cats back and destroys your base in one shot. The trick is to destroy the base without killing anyone, although there are other ways.
Use low damage knock-backing cats, such as Dread Pirate Catley and Brah Cats. As the enemy limit is 3, these cats can knock the 3 One Horns back behind the base without killing them, allowing you to destroy the base with no chance of an Assassin Bear destroying you. Also, try using cats that have a decent shockwave or maybe cats in the cradle.
Cat combos can help a lot, especially KB up, but also for the worker cat. This strategy becomes easier as the stars difficulty increases.
- The Assassin Bear that appears in this stage deals the second highest damage per hit in the game.