CAT DAY

CAT DAY is an event stage added in version 8.9. It appears on the 22nd of every month. It drops 22 Cat Food upon completion, but can only be played once per month.

Battleground
As soon as the battle starts, the Cat Day Cake will spawn with a boss shockwave. Firework Guys and Doges are occasionally deployed as peons.

Reference

 * https://battlecats-db.com/stage/s01209-01.html