Rongorongo is the 6th and final stage in Spring, Sprang, Sprung.
Battleground
Near the beginning, a Doge Dark and a Shadow Boxer K will appear. (Order: fight begins, ..., Doge Dark, ..., Shadow Boxer K)
Doge Dark respawns after 20 seconds; Shadow Boxer K respawns after 30 seconds.
When the enemy base takes enough damage (100%→75%), an Easter Duche and an Easter Bunny will appear. A few seconds later, another Easter Bunny appears.
When the base is down to 50% health, about 4 Easter Bunnies and 2 Easter Duches will be spawned.
The base deals 3750 damage.
Strategies
Strategy 1
Lineup: Mohawk Cat(20+19), Eraser Cat (20+19), Macho Leg Cat (20+19), Dragon Cat (20+19), Valkyrie Cat (30), Bahamut Cat (30) and any Long Distance cats.
Unlike any stages where the enemy base can do Shockwaves that cover almost 100% of the field, it's not necessary to stall enemies outside of the enemy base's range. The player can just spawn a lot of heavy hitters to knock all enemies behind its base and damage the base in the process.
Strategy 2 (ft. Li'l Shirou and Unknown Cat)
This strategy is for those ones who have won EoC Chapter 3 and have all treasures from each EoC chapters. It is reccommended to have at 100% Legendary Cat Sword and Legendary Cat Shield treasures. This strategy was tested to achieve the first star, and it isn't to speed run the level.
Lineup: Macho Cat (20 + 7), Crazed Macho Cat ((10), optional, you can use another meatshield instead of it), Samba Cat (20), Wall Cat (20 + 9), Li'l Shirou Cat ((27), optional, you can use another Anti-Black unit, like Kasa Jizo (first form) or Ring Girl Cat), Paris Cat (25), Dragon Cat (20 + 8), Valkyrie Cat (20), Bahamut Cat (20), Unknown Cat ((15), Unknown is for knockbacking enemies, but other Lugas or heavy damage dealers should be nice).
Upgrade your wallet to level 2. Don't send anything until the Doge Dark appears. Then, start sending meatshields, Li'l Shirou and 4-5 Paris Cats to kill the Doge Dark and the Shadow Boxer K that appears a little later. Upgrade your wallet, and don't send anything, because the base will kill them. Get money and wait for the others Doge Darks and Shadow Boxer K. Kill them and repeat the progress. Save your money to max capacity while sending Paris Cats and Dragon Cats to reduce Enemy Base's health to 75%. Don't worry if you have to repeat the progress a third time.Also, at this point you should have your Worker Cat at max level.
When you reduce Enemy Base's health to 75% and the Easter Duche and the Easter Bunny appear, send all your meatshields, Valkyrie Cat and Bahamut Cat. Also, don't stop meatshielding and sending Paris Cats, Dragon Cats and Li'l Shirou when you have it. If you do it fine, your Bahamut Cat won't die. Also, get your money to max.
When you reduce the Enemy Base's to 50% and the 2 Easter Duches and the 4 Easter Bunnies appear, send Nekoluga, don't stop meatshielding and sending your Paris Cats, Dragon Cats and Li'l Shirou. When you have already defeated them, go to the base and win!
