Festival Gross is the fourth Crazed Cat Stage. It appears on the 12th of every month.
Crazed Gross Cats will be spawned at a slow rate during the battle alongside some basic peons. The overall strategy in this stage is to send out tanky units that can withstand several blows from a Crazed Gross Cat, such as Island Cat, Crazed Whale Cat, King Dragon Cat, or wave-immune/Wave Shield units. Try not to let the Crazed Gross Cats stack, and avoid using meatshields so as to minimize the number of Shockwaves being created.
Strategy 1 (Uberless)
Battle: start by saving money, and when the first Crazed Gross Cat is halfway to the base, spawn Macho Leg, Paris Cat, Dragon Cat and Jamiera Cat. Spawn Bahamut Cat when you have enough money. The main method for this strategy is to build up an army of King Dragon Cats and Paris Cats and hope to not get hit by waves too often.
Strategy 2 (Wave Shield)
The player does not need any high level cats for this strategy except for a wave blocker.
If you have a Wave Shield such as Octopus Cat, the level becomes a joke as the Crazed Gross Cats' single-target attacks will only hit one cat at a time, so just summon the Unit with many meatshields, some attackers and fight as you would do in a regular level. Any setup with a Wave Shield and 3-4 75¢ meatshield will work. The best strategy would be to have several Octopus cats and many 75¢ meatshields in the front and Paris, Dragon, Crazed Bahamut and True Valkyrie in the back. Anti-traitless ubers would also help.