This is basically a heavily watered-down Crazed Cat with a Black attribute, but it gains a strength magnification as the player progress through the event. Luckily, it only attacks one cat at a time (single target), but spawns in huge groups in the last stage. To beat them, you can outlast them as their spawn rates eventually decrease to a manageable level.
Strategy 1 (For 222 Incident)
Lineup: Cat, crazed cat, tank/crazed tank, Jiangshi Cat, Flower cat(optional), Paris cat, Awakened Bahamut, crazed lizard. crazed gross/bird, optional damage-dealing uber or anti-black of choice(Slow or Freeze priority, knockback to be considered)
If you didn''t bring Rich Cat, upgrade worker to Lv.4. Killer cat should come out now, waif for it tostall it with only cat and crazed cat. If the meatshields stack, you've done it right. Do this and upgrade your worker to max. Shortly after that, the second killer cat should spawn. Now, spawn all four of the meathsields(cat, crazed cat, tank/crazed tank, and Jiangshi.) Jiangshi's damage should finsih off the first Killer Cat. Keep spamming all four meatshields until the second Killer cat is knocked back twice. Now, only spawn crazed cat. Jiangshi will finish it off soon.
When it is dead. Stop spamming, and corrupted cat cannon will fire and kill meatshield left EXCEPT jiangshi, who survives once.When Jiangshi reaches the enemy base, spam meatshields again. The timing should cause the group of Killer Cats to move about to the middle of the battlefield. Now, spawn your attackers, and when attackers reach, spawn awakened bahamut. Awakened Bahamut is likely to get knocked back once, and then would stay out of reach of Killer cats. When Killer Cats go close to bahamut again, wait for bahamut to finish his attack animation (when he makes some sort of energy come out from his body, then claws the enemy again) shoot the cat cannon. Bahamut would half-glitch through the Killer Cat group and knock them back due to high damage.
When group is defeated, spawn only jiangshi , and then destroy the base at your leisure.