*Whew, apologies for such a long post.*

King Krogmo is looking for the best of the best Spiral Knights to challenge him in his new venue, deep within the Clockworks: The Chaos Coliseum!

The Chaos Coliseum carries a major, though not necessarily 'new', mechanic that is present throughout most or all levels. Lockdown style shields are gained at the beginning of each level, though they can be changed out once or twice per level to allow people to switch around playstyles. The shield stats may have to be slightly modified (the +10 health on some of the shields, definitely) but the key mechanic of each shield would stay the same.

Striker: Shield button speeds you up, you also do more damage.
Guardian: Shield guards you and, after a short wait, creates a barrier for allies as well.
Recon: Shield renders you invisible to monsters and, with the recon pulses, lowers the defenses of monsters.

Puzzles can consist of the need for a variety of party members with different abilities.

1. Large trap areas, disabled with a button on the far side, that need a boost of speed to make it across without damage.
2. Halls filled with respawning turrets that are easier to get down with invisibility. Switch at end destroys turrets.
3. Permanently activated traps that can be walked over painlessly using the Guardian shield.
4. The combination of floor traps, rockets (from Roarmulus / Blast Network), and Siege Wheels (from Firestorm Citadel), and raised floor panels (which spawn monsters).
5. Occasional Blast Network style bombs that launch waves horizontally and vertically to damage players.

New monsters may consist of:

Ogre: A large monster that uses large, 180 degree swings, tosses scatter bombs (like gremlin bombers), and farts clouds of poison. Has enormous amounts of defense, takes ~40% of regular damage. Each Recon mark reduces their defenses up until about 3 stacks.
Spiral Knubs: NPC Spiral Knight lookalikes with randomized armor and randomized weapon (sword, gun, AND, bomb types) that occasionally use their (breakable) shields to stop enemy attacks.

The whole dungeon would probably be much more difficult to solo than Firestorm Citadel, due to the classes, but probably not impossible to a skilled and lucky enough player. A good group of 3 or 4 should have one of each class at least.

Now, finally, onto the boss:

King Krogmo is a beast, he's about as big as Vanaduke and wields a scepter in one hand and a sword in the other. He's immune to freeze and primarily does normal and shadow damage. Krogmo takes about 40-50% of usual damage unless a Recon marks him, like the Ogre.

He has several moves:

1. Krogmo raises his scepter then smashes it into the ground, leaving a cloud of shadows for about 8 seconds which damages anyone who enters it, with possibility for short duration curse on strike or entering the cloud.

2. Krogmo raises his sword and whirls it in a 360 spin, leaving a cloud of poison for a few seconds. The sword strike can also poison.

3. Krogmo raises sword and scepter and bangs them together in mid-air. A few seconds later, a cloud of either poison or shadow covers the entire arena. Those hit with shadow are cursed and damage, those hit with poison are poisoned and damaged. Anyone standing under a Guardian's bubble is not affected.

4. Krogmo jumps to a new place and stomps the ground, causing bombs to fall from the sky. They can be either the Blast Network bombs or regular bombs (for balancing). These bombs do reduced damage to a Guardian's shield. The amount of bombs increase for every new phase.

5. Krogmo will bellow, opening one of the four gates in the arena. Spiral Knubs will begin emerging from the gate at a steady rate until the gates are closed. A button near the gate must be stepped on to shut it. Strikers can get to the button the fastest, allowing less Knubs into the battle.

In Phase 3 he gains a new move:

5. He raises his scepter and a bubble surrounds him. He begins to heal underneath the bubble until it is broken by player attacks.

In Phase 5 he gains 2 new moves:

6. Bombs constantly rain from the sky at a steadily increasing rate.

7. Krogmo's bellow opens 2 gates at once, instead of one.

At 66% and 33% health, Krogmo will become immortal and jump out of the arena before initiating a minigame for phase 2 and 4. The minigames are chosen at random with hearts as the prize for winning. I've come up with a few, though there should probably be a couple more to round the list out and make sure each fight feels a bit more unique, fun, and chaotic.

1. Race to the finish line: Characters are divided up into lanes and must make a run for it to the end of their lane through a series of traps and turrets. If one player makes it to the end the minigame is over, possibly with extra hearts for the player that makes it first.

2. Checkpoint hold: Players must hold off an onslaught of infinite enemies while taking over a series of checkpoints, Lockdown style.

3. Battle: Danger Room style battle with the minigame ending when all the monsters are dead.

4. Survival: Pulsing Blast Network style bombs are dropped into an arena and players must run around without shields to try and survive until the timer runs out.

5. Lucky Bonus: Players throw pots to hit moving targets which drop coins, heat, and hearts until a timer runs out.

Once Krogmo is defeated, he takes a bow and thanks the players for the fun before giving them tokens (probably different from Krogmo tokens, or in addition to them).

Additional Mechanics:

Bribe: Players can fill up the energy bar before the battle, like in the lobbies before PVP games. If the bar is filled you may get a bonus for beating Krogmo or (possibly) an easier fight.

Wager: Talk to Krogmo's assistant before the match to make a wager. This doesn't cost energy, but requires all players to agree to the wager. If the wager is made, Krogmo becomes much more powerful and difficult to kill. He might also gain some new moves. If you beat Krogmo, you get double or even triple the tokens, or some other large bonus, depending on balancing. This mechanic would likely only be for experienced Guilds looking for a real challenge.