What if there are a ton of destructible (and crown-dropping) Isotrode and Mecha Knight corpses littering the area, and some of them activate and try to kill any Knight that gets too close to them? Kinda like the Trojan statues from The Silent Legion and the Almirian Crusaders from Legend (or was it Legion) of Almire. And I finally have an idea for one of the final battle rooms:

In the deeper part of the industrial half of the swamp (basically metal floors and walls, but with enough damage that it's basically eaten by the overgrowing swamp) there is a party button inside what looks like an old metal reclamation area. A rusted crane hangs over four piles of inactive Isotrodes and neglected Mecha Knights. Three of the piles are located at the edges of the room, but the fourth is located in the middle of the room, and it has what looks like a giant wrench claw thing sticking out from on top of it.

Pressing the party button will wake up a large pack of Rabid Wolvers and Virulisks who have decided to make this place their home, and will also awaken some of the Mecha Knights and Isotrodes in the piles of metal. The fight lasts 3 spawns, during which there is no need to destroy the Isotrodes and Mecha Knights, who always respawn in a group of 2 Isotrodes and a Mecha Knight each, but each picks a random pile to pop out of. First spawn is 8 Wolvers and 5 Virulisks. Second is two Alpha Wolvers, 8 smaller Wolvers and 10 Virulisks. In the third one though.....

The room shakes. You hear an ominous noise, sounding like metal grating on rusted metal, coming from the middle pile. And then suddenly, the pile explodes, sending Isotrode and Mecha Knight parts into the air, as a hulking mechanized monstrosity held together by nothing but rust and anger wakes up from under it!

It's a large Construct with giant mechanical wrenches for arms, a Retrode's head (but bigger, and with red eyes) and a hiccupping rocket booster in the back. It has four attacks. One would be to simply slam its arms on its target's head. The second would be to simply fire its oversized Retrode laser. The third is a dash, and this is where things get confusing. Occasionally, it's booster will cut out halfway through the dash attack, causing it to trip up and do an accidental AoE body slam. The fourth (or fifth if you count the AoE body slam) would be to dash while firing its Retrode laser in a zigzag, causing it to asplodinate whoever tries to trail behind it. Thankfully, it has no frontal or rear shields of any kind. Just one phase and lots of HP.

That's assuming it becomes a Danger Mission of course. No Danger Mission= replace scary giant mecha with a Battle Pod, 5 Wolvers, and 5 Virulisks.