Realm of Carnage (Deadly)

Realm of Carnage is a special stage where you can fight Hannya. When clearing this stage, you have a chance to unlock Express Cat (guaranteed if you use a Treasure Radar). This is a No Continues stage.

Battleground
Realm of Carnage features a unique boss called Hannya, which appears as a boss after 10 seconds.

Bores appear as support starting from 33.3 seconds.

R. Osts appear as support starting from 83.3 seconds.

Ginger Snaches appear as peons occasionally, but stop spawning after 160 seconds.

The map is quite long, but Hannya has nearly the same range as Sunfish Jones and damage that nearly OHKOs any of the Normals, Specials and Crazed except for high level Jamiera and Islands. The supporting enemies are what make this a challenge as they are easy pushers, especially the R. Ost which can easily wreak havoc. This is pretty much an endurance battle where one mistake can lead to disaster and tragedy.

Strategies 1 & 2
OR
 * Row 1: Lion Cat, Madam King, King Dragon, Crazed Dragon, Macho Leg Cat
 * Row 2: Crazed Wall Cat, Eraser Cat, Island Cat, Crazed Whale Cat, Awakened Bahamut
 * Cat Combos: Lion King (Strong Effect UP (Sm)), Three Kings (Unit Defense UP (Sm))
 * Row 1: Maiden Cat, Koi Cat, Madam King, Lion Cat, King Dragon Cat
 * Row 2: Eraser Cat, Crazed Whale Cat, Island Cat, Crazed Dragon Cat, Awakened Bahamut
 * Cat Combos: Lion King (Strong Effect UP (Sm)), Three Kings (Unit Defense UP (Sm)), Seasons of Love (Strong Effect UP (M))

Battle Items: Rich Cat (optional but helpful), Treasure Radar (only if you're sure you are able to beat the stage)
 * Note: This strategy requires Level 30 Crazed Cats and high-leveled basic cats.

Start off by deploying some Crazed Whales (For Lineup 1: and Crazed Walls) to stall the Hannya, while also upgrading your Worker Cat to about Level 3 or 4.

When the first Bore arrives, stop deploying Crazed Walls and start deploying Crazed Whales and Island Cat only to damage the Bore (and Crazed Dragons and King Dragon and [For Lineup 1: and Macho Legs] only if you have the money) and continue slowly upgrading your Worker Cat. Killing the Bore before R. Ost arrives is crucial as dealing with them both will be extremely troublesome.

When the Bore is defeated, continue deploying Crazed Whales and Island Cat to deal some damage to Hannya. When R. Ost arrives, stop deploying Crazed Whales and Island Cat and start deploying Erasers (For Lineup 1: and Crazed Walls) as meatshields, and deploy Awakened Bahamut, Crazed Dragon, King Dragon (For Lineup 1: and Macho Legs) to damage the R. Ost, while continuing to slowly upgrade your Worker Cat. Awakened Bahamut should easily take R. Ost down.

Start sending only Crazed Whales and Island Cats out to damage Hannya. Repeat the above when the Bores and R. Ost arrive and you should be able to win the stage eventually.

Note: Manage your money properly and do not unnecessarily deploy troops, or it may result in your loss.

Strategy 3

 * Lineup: Jiangshi Cat, Lion Cat, Maiden Cat/Wrestling Cat, Madam King, Koi Cat, Crazed Dragon Cat, Macho Leg Cat, Island Cat, Crazed Whale Cat, Awakened Bahamut Cat.
 * Cat Combos: Strong Effect Up +20% and +10%.
 * Used Cat Levels: Normal Cats: 20+50, Crazed Cats 40, other: 30.
 * Battle Items: Treasure Radar (if necessary), Rich Cat, Sniper the Cat (optional)
 * Begin the battle by spamming Island Cat and Crazed Whale Cat, do the same when the first Bore appears, as the Whales and Islands will deal with them just fine.
 * Start to spam Jiangshi Cat when the R. Ost is about to appear. Stop spawning Islands and Whales but Macho Legs and Crazed Dragons instead.
 * The first R. Ost will not be killed when the second Bore appears, start to spawn Islands and Crazed Whales again, if the player has Wrestling Cat, her ability will help blocking both the Bore and R. Ost for a bit.
 * The second Bore will be killed first, then the first R. Ost, only spawn Island and Crazed Whale to damage Hannya until the second R. Ost appears, do the same strategy to deal with it. If timed correctly, Awakened Bahamut will do some decent damage to it, using his second form is also helpful when dealing with both of them.
 * The player will beat Hannya before they encounter the third Bore, or the third R. Ost.

Strategy 4

 * Lineup Row 1: Kiss and Koi, Maiden Cat, Madam Bride, King Dragon Cat, Lion Cat,
 * Lineup Row 2: Jiangshi Cat (30+3), Paris Cat (40+5), Crazed Whale (40), Island (20+36) and Divine Kuu (30).
 * Battle Items: Rich Cat, Sniper The Cat and Treasure Radar (optional)
 * Send out nothing until the first Bore come out, when that happens use Crazed Whale and Island to kill it and the Ginger Snaches.
 * Once the Bore is defeated keep spamming Crazed Whale and Island. When R. Ost comes out, stop spawning Crazed Whale and Island and spawn Kuu, Jiangshi and Paris. Send Kuu out after R. Ost is hittng the Jiangshi spam, keep doing this and done you now have Express Cat.

Strategy 5

 * Lineup Row 1: Jamiera Cat, Dancer Cat, Beefcake Cat, Lufalan Pasalan, Paris Cat (40+10)
 * Lineup Row 2: Jiangshi Cat (40+19), Maximum the Fighter (40+13), Crazed Whale (30), The Peach Devils (36), God-Emperor Kamukura (40)
 * Battle Items: Rich Cat, Sniper The Cat (optional) and Treasure Radar (optional)
 * Cat Combos: Resistant Effect Up S (No Stage Fright), and Unit Defense Up M (Arm Day Everyday)
 * At the start of the battle, send out Maximum the Fighters and Crazed Whale Cats for stall and defeat the Ginger Snaches and the 1st Bore.
 * When R. Ost appears, start spawning Jiangshi Cat and Paris Cat. You can also send out either of Peach Devils and Kamukura, or even Lufalan Pasalan (kinda risky but may OHKO R. Ost given a high level and damage).
 * Repeat the pattern for stalling R. Ost and Bore with Jiangshi and Maximum the Fighter midbattle, while keeping tabs on calling the occasional Kamukura and Peach Devils to beat them alternatively.
 * This strategy focuses on giving the extra "stop" and "slow" effect to Bore and Hannya, so it may have some issues with other strategies, while giving high damage to R. Ost and Bore too. This one is also kind of slower than the others but it will kill around 4-5 R. Ost and Bore, in the run. (There's another strategy but I'll have to review it, it was noted down.)

Strategy 6 (Ft. Kasa Jizo)

 * Lineup Row 1: Madam Bride , King Dragon Cat , Lion Cat , Roe Cat , Awakened Bahamut
 * Line u Row 2: Eraser Cat , Crazed Wall/Manic Eraser , Kasa Jizo , Island Cat , Crazed Whale/Manic Island
 * Battle Items: Rich Cat (crucial), Treasure Radar (optional)
 * Level Requirements:  All Basic Units at least +45 (If you don't have Manic Eraser/Manic Island, you must have +50), Hypermaxed Crazed, Hypermaxed Jizo, A. Bahamut (30), Roe Cat (35)
 * Send out 3 Manic Erasers at the start.
 * When Hannya spawns, spam both Islands and send out Roe Cat.
 * Do this until R. Ost spawns.
 * When the demon spawns, kill all Ginger Snaches and let A. Bahamut, Kasa Jizo and King Dragon kill him, don't forget meatshields.
 * When R. Ost dies, chances are Bore has already spawned, kill him and then move on to Hannya.
 * Keep on spamming both Islands & Roe Cat until Hannya dies. (Please note, he won't die the moment the 2nd Bore is down.)
 * The R. Osts and Bores from then on will be very easy to deal with.

Strategy 7 (Ft. Pai-Pai and The Peach Devils)

 * Lineup Row 1: Madam King, King Dragon, (20+30) Lion Cat, Eraser Cat, (30+25) Crazed Wall/Manic Eraser (20)
 * Lineup Row 2: Island Cat (20+30), Crazed Whale (20), Awakened Bahamut (30), Pai-Pai Z (40), The Peach Devils (30)
 * Battle Items: Rich Cat (required) Sniper The Cat (optional)
 * Use Crazed Whales and Islands to stall Hannya. When Bore is realeased, use Erasers and summon Pai-Pai. (Continue spamming Crazed Whale/Islands.)
 * When R. Ost comes out, Use Peach Devils and King Dragon, along with Erasers and Pai-Pai. If you want, try to time an A. Bahamut.
 * After R. Ost is gone, use Pai-Pai to kill Hannya.
 * Rinse and repeat if more Bores/R. Osts spawn.
 * ONLY use Sniper if no Peach Devils/Pai-Pai are on screen and R. Ost is a threat.

Strategy 8 (Ft. Divine Kuu and Roe cat)

 * Lineup Row 1: Madam King, King Dragon, (20+30) Lion Cat (Three Kings and Lion King) Divine Kuu, Macho legs (mine was +42)
 * Lineup Row 2: Manic eraser (30+) Eraser cat (mine was +44) Crazed whale (30+), Island cat (mine was +30) Roe cat (30+)
 * Battle Items: Rich Cat (Optional but helpful) Treasure radar (optional)
 * When the battle starts upgrade your wallet once then spawn Roe cat to stall. If you don't have rich cat use this as an opportunity to upgrade wallet to 4. When bore comes out spawn eraser, Manic eraser, Roe and both fish to kill the bore, If you don't have rich cat just spawn two/one of each and upgrade wallet as Bore gives a lot of money.
 * When the Bore dies ( as long as the R.ost isn't spawned yet) only spawn both fishes and both erasers. When r.ost gets to Hannya stop spawning cats, wait till it is ahead of him THEN spawn Kuu, dual erasers dragon and macho legs. Do not spawn kuu if R.ost has enemies that may make her miss in front of it, instead spawn a crazed whale or wait for dragon and macho legs to kill them then spawn kuu. She with macho legs and dragon should be able to kill it.
 * As soon as you have killed the R.ost start spawning Both fishes and Roe only to prepare for the next Bore, this will let them deal damage to Hannya and easily kill the next bore.
 * Rinse and repeat until you win, there is a few RNG factors but this worked twice in a row for me.
 * Notes: Do not spawn kuu unless their is an R.ost in front of Hannya, Fishes can deal with Bore but not with R.ost. Same with macho legs and king dragon, they are used for killing R.ost and nothing else, this is because this stage doesn't have many peons so it doesn't have a very good cash flow and macho legs and king dragon would spend too much money on minimal damage against hannya. Also kuu is almost necessary for killing R.ost unless you have a high level dragon (+50 or more) otherwise they wont kill it before the Bore spawns and at that point you instantly lose unless R.ost has had three knock-backs ( and even then single target can screw you).
 * Strategy 9(ft. Pai Pai):
 * Battle items: Rich cat(required) Treasure radar(optional)
 * You need a defense up M combo (I used eye of the storm) for row 1
 * Row 2: maximum the fighter lvl 41+, Island cat lvl 20+27 or higher, Crazed whale cat lvl 20+, Pai Pai lvl 24+, A. Bahamut lvl 30
 * NEVER SPAWN THE COMBO CATS. At the start wait for Hannya to spawn. Right after it spawns, spam Island, crazed whale and maximium Until R.Ost spawns. Bore should die. Let R.ost get close to the base and kill the ginger snache with island or crazed whale if there is ginger snache and spawn a maximium and right as R.Ost attacks, spawn bahamut and everything else. If done correctly, then bahamut should kill R.ost. Right after R.ost dies spawn Pai Pai and everything else to do damage. Eventually Bore spawns. Then just keep spamming and it should die. When R.ost spawns let everything die. Even Pai Pai. Then time another bahamut and spam everything. When Pai Pai is recharged again, spawn it. Hannya should die, and spam everything to win. Bore might spawn but don’t worry. Just keep spamming. Good Job, you beat the stage!

Strategy 9 (Speedrun, by Chillhola)

 * Lineup Row 1: Manic Eraser Cat, Maximum the Fighter, Elemental Duelist Cat, Manic Island Cat, Divine Kalisa
 * Lineup Row 2: The Peach Devils, Divine Kuu, Sea Mistress Ruri, Pai-Pai Z, Awakened Bahamut
 * Battle Items: Rich Cat, Speed Up (keep activated for the whole battle)
 * Other Cats: You could bring Sushi Cat as a meatshield or iCat as a freezer.
 * Do nothing until a Ginger Snache spawns. Lure it close to the base and spam Manic Erasers. When the first one dies, spam Manic Island as well, along with Maximum and Duelist. Stop spawning Manic Erasers when the Bore is close to the base.
 * When the Bore appears at your base, spawn Pai-Pai and Ruri, then continue spamming Maximum, Duelist, and Manic Island.
 * When the bore dies, spawn Peach Devils and Kuu, then you will take on Hannya. Continue spamming Maximum, Duelist, and Island. Hannya's health will deplete very fast. When Hannya knockbacks once, spawn Kalisa. Once Hannya is dead, spam Manic Eraser again as well as Maximum, Duelist, and Island to defeat the R. Ost that appears. Once R. Ost knockbacks 3 times, summon A. Bahamut.
 * Just keep spamming Eraser, Maximum, Duelist, and Island. The base will die very soon.

Trivia

 * The enemy base's HP is composed of two 666s, believed to be the "Number of the Beast".
 * The River Styx is a river from Greek Mythology which makes the boundary between the Earth and the Underworld. Source and more info.

Reference

 * https://battlecats-db.com/stage/s01117-01.html