So right now, Vanaduke belongs in the Fiend Family, and his minions are about 70% Undead. How about we switch the roles?

I present you.... *drums play*
The Kat Heroes - Preowa, Scraith, and Torair! Margrel already has his (mini)boss battle so I'll count him out.
World name:
Plot stuff: The Kat Heroes have been reading tomes in the Owlite Academy of Magicks and used dark magic inside to awake the now-dead Owlites, mutating them into dark monsters! (For some reason I think The Swarm should be involved... Don't think the Kats would be such Madmen. If this is considered, I'd like them to have Pink/blackish swarm-like eyes.)

The world name could either be Owlite Academy of Magicks, Growlite Academy of Magicks, Cursed Fortress, Everdark Castle, or whatever OOO wants to name it.

New monsters
Preowa, the Gunslinger Kat - A Kat with arms and legs, as tall as a Dreadnaught. She (Correct, OOO) wears grey/silver robes. Has dual magnus-psychics guns that fire burning candles (Like in Candlestick Keep) that have a chance of setting you on fire.

Torair, the Demo Kat - Same as above. Wears a green/brown Demo Suit and drops special bombs that have a disturbing, hissing sound and cover as much as big he is. He needs to charge the bombs tough. Sits on a floating throne until Preowa dies, occasionally shooting bullets out of his mouth.

Scraith, the Swordsman Kat - As tall as a Dreadnaught, has arms and legs. Sits on a floating throne, watching the other Kats battle. Occasionally shoots bullets out of his mouth while on the throne. When they both die, he hisses/meows into the air as if hurt badly and Fiend-like paintings appear on the ground. Claws grow on his hands

Growlite - An undead Owlite cursed with dark magic that turned him into a Fiend. Can fly and attacks by diving (Also the only moment he can be hit) and if you surround him, he'll do a wing swipe (Similar to Leviathan charge, less knockback). For some reason, these creatures growl.

Growlite Magician - An undead Owlite Magician cursed with dark magic that turned him into a Fiend. Can himself use magic that shoots projectiles, inflicting a random status. After attack (Which is the only moment he can be hurt) he starts floating and moves to a safer distance before attacking again.

Egg Growlite - A Fiend Mini. has a jelly like attack, and is like a Shankle that moves freely - it has to show it's head through a hole on top of the egg if you want to kill it.

Gargoyle - Stony, creepy, but slow walking monsters with fast attacks and shields that take 2,600 damage to break (Note that the levels are placed on Stratum 6. They will bring their shields up every time they are shot like Almirian Crusaders). Have strange tails with spikes that can protect their back. They are strong against every damage type excluding Normal, and have an unnatural weakness for fire. (Yes, I am trying to give the V-Pepperbox a purpose.)

Big Gargoyle - Same as above, bigger, and faster. Has big fat muscled hands. Walks like a gorilla and has a slam-the-ground attack that knocks back like a Trojan attack. Can also dig the ground under themselves to pick up a boulder to throw. The boulders work like t2 Gun Puppy rockets, except inflict Shadow and no fire. Also has no shield. Has HP of 4 Trojan Knightmares, but as I said, no shield. Only appears in arena rooms of the world.

Demon Hand - A small, Silkwing-sized floating stony blocky hand that has a Curse/Swarm-like eye inside. Can pack a punch and shoot a projectile out of it's eye.

Grimmy - A slightly smaller Grimalkin that can be killed similarly to a Howlitzer Kamikaze Head. Only appears on D28 as helpers for the Kats. No candles here, tough.
Note that only the New enemies, Silkwings, Gorgos, Howlitzers, Spookats and maybe some slimes and beasts appear here. (Devilite Business, Gremlin patrols, or stuff would seem strange here, don't you think?)

The maps would be completely up to OOO, so long there big and there's 5 of them. I preffer if this is harder than FSC and has better payouts, too.

BOSS INFO:
Boss Arena: The kats would be sitting on floating thrones, Preowa on the left, Scraith in the middle, and Torair on the right. The battle room would be a balcony-like thing similar to Black Kat arenas in Candlestick, except without the bookcases and the pages lying on the ground. The exit & loot room would be over a massive gap, and the only way to get over is to kill the Kats (Their thrones will be stuffed over the gap to form an unstable bridge that falls when all party members get to the other side).
Boss Cutscene that happens after everyone steps on the party buttons: Torair stands off his throne, hovering/floating/jumping over to the platform. He notices the players behind the gate, hisses, runs up to Scraith, says something, afterwhich the message from Scraith will appear (Like Vanaduke's speech): Who are you?! Did the Owlites send you?! Well then, prepare to die! After that, all Kats meow with their heads into the air.

Battle: Each Kat Hero has 2 phases - one wherein he uses his standard weapons (being pretty much a regular damage sponge), and one wherein he uses both standard weapons, and Magick. Magick phases would work differently for each Kat hero:

Preowa can become invisible. However, a Mirror will be raised to the north of the arena during this part. Unlike Recon/Ghostmane Cloaks, you won't be able to see if they are near you, instead you have to look at the mirror where she appears. Her bullets can be seen in the actual arena, tough. You can't see yourself and teammates in the mirror. The mirror breaks as Preowa dies, revealing the other Kat heroes.

After Preowa dies, the 2 others hiss. The throne Preowa has just sat on breaks, and the broken parts float over to where the gap is and form the first part of the bridge. This is the same for the 2 other kat heroes.

After that, Torair jumps off his throne, and starts spamming bombs of the size and charge time of a Super Blast Bomb (3*) with a 5* Kat Helm effect (instead of the eyes) and a tone of dark green. These do Shadow Damage.

His magick phase is that his bombs are now the size of a 4* Blast Bomb, and deal more damage. He also has a shield over his back+side armor now.
The special about Torair is he has 3x the HP of other Kats.

After Torair dies, Scraith cries/meows into the air. He then jumps off, and spike traps appear in the borders of the arena. He has a shadow Wild Hunting Blade like sword, that is as fast and does shadow damage.
When he moves in his Magick Phase, he will be able to teleport around the arena and his Shadow sword will be wider, and will also do Ghosts Hits (Which it previously didn't).

Preowa and Torair have a special attack tough - Shove. It knocks players back, dealing 1 half-pip of damage and a chance of inflicting minor stun.

After the thrones form a bridge and the party goes into the loot room, they can notice three Mewkats (one of each Kat hero colour scheme) that would act as one NPC saying:
"Thank you, warrior! The curse is now broken, but keep your eyes open. It might try to take you, too." After that the Mewkats dissappear in a cloud of smoke.

So wait, is this world curse-themed?
I'm not entirely sure. The curses I mentioned were pure for explaining things. If OOO feels like this should be a Curse World, I'd be fine with it. And a place where Black Kats (no tokens tough) appear not during Kataclysmic Confrontation would seem nice, too.

Token and Token items
The token would be... I don't know, a Kat claw?

Items that could be purhcasable for tokens are:
Hiss Bomb (2*) for 30 tokens. This is like another Nitronome that deals Shadow Damage but has -CTR 2. It would be upgradeable till the 5* but I'm not sure about the names.

Pepperkat Gun (2*) for 30 tokens. Shadow/fire version of the Valiance with ASI -2 and upgrades till 5*. The names would be: Spooky Pepperkat Gun (3*) Candle Gun (4*) and Flaming Candle Gun (5*). Due to the fire, it would have damage comparable to Winmillion in Shadow damage.

Spookat Claw (2*) The shadow cutter carried by Scraith. Again, has upgrades. Is a bit slower than regular cutters. Not sure about the names either.

Mewkat Shield (4*) for 45 tokens. Could be upgraded to shields that give Sword ASI, Gun DB, or Bomb CTR - all High. These would have Shadow-only (So that the CoA won't get obsolete) resistance, with some freeze resistance.