So I've had a few Ideas floating around in my head./

1- A Boss themed world based on rivers and or open water.
Yes I know I am not the first to suggest a water theme, but I think it really should be put into the game.
The monster can travel through 'portal puddles' too and away from you. Much like the Wolvers of tier 3 but with a few predetermined locations. Like a biomechanical fish with feet that hops out shoots at you, and hops back in to appear out of another 'portal puddle' of water. I am not quite sure if a new status or damage type should be included, or if perhaps one could be heavily used based on the few lines of monster. This transfers to the next part of this theme, where as the boss levels include our knights to travel through raging waters, either a 'shallow river' or a large wading lake style scenario. The heavily implicated status effect of this world would be stun, and I will explain why. So as our characters progress through water world, and timed series of 'large waves' will come crashing through the walk-able terrain. Our water themed monster will be unhindered, but our knights will have to find quick cover next to a solid bush/stone or terrain to hold themselves up against so as to not get washed back a large distance in which they would need to travel. Any characters stunned during the event will find it hard to take cover and be washed back down through the course :). These waves can leave puddles, in which our fishy fiends will pop out off occasionally and pester once more.

2- A boss idea, consisting of my favorite enemy in the game: the Chromalisk :)
I don't care that we've already had a beast boss, it's not about making a boss for every monster type. it's about having unique and fun play. So my suggestion is simply this. A large 'mother-hydra chromalisk' (and by hydra I don't mean mult-headed, you'll soon find out). This fearsome looking chromalisk is, as stated the mother of all chromalisk, and will have a multitude of eggs that constantly hatch small nuisance chromalish, much like the bots in the twins dungeon. The boss has a few unique attacks. Her main and very important ability is to randomly rotate through colors, each representing a status effect, like a slot-machine, during which the beast is still invincible. Once a color has been chosen, the Hydra-chromalisk will rotate spewing a line of globby-goo that will inflict a small amount of damage and the based status effect. After a rotation or several, the boss will stomp around and begin licking about with it's massive tongue, and if your knight should be unfortunate enough to be hit, (although this should be easy to dodge unless you are stunned, frozen or shocked) the Mother- Chroma will gulp you in, harm you, heal herself a small portion of health, and spew you back out. The knights main task during this period is to hit the tongue of the mother chroma while she attempts to grab a snack. Doing so will knock her out for a few moments, in which time a knight (one not all) must walk into the belly of the beast and do your damage ( during this time the mother will not be able to harm you, and once she awakes you will be spewed out with no damage done). Another unique idea I present to you is that while the young chromalisk emerge, any spewed on during the course of the hydra rotation will attain the status type variant as their source of spew weapon.
My suggestion for weapons that may be won using tokens from this boss are as follows:
A blade that act like a chroma tongue, when swung it begins small and stretches out further than any other sword. Perhaps the first swing grabs an enemy, and pulls it to you for a second swing? Like a yo-yo.
A 'Mother Chroma-scale shield' or 'mirror shield' that will block piercing, but with a unique effect, should an enemy attempt to harm a knight while blocking, any status that monster may have tried to afflict, the shield is now resistant to. For example: Should a Lumber swing at you and you succesfully block, your shield is suddenly pretty decent at resisting stun. (although I use lumber in this reference and I realize that they are one of few monsters that can afflict two statuses, I would suggest that the shield only be able to absorb one status, as two would be too many.) The idea is, that when sward against a group of monster afflicting one status, you will become resistant to it while blocking, but should a different monster with a different status hit you, you will be resistant to the newer status, and lose protection from the old.

3. My 3rd suggestion consist of a pvp arena in which your knights free-for-all against one another in a sort of dungeon, surrounded by invincible zombies. These rooms consist of small chambers, in which the doors blockade the exit, and can only be opened by switches. The idea is to trap the other knights in a room full of unstoppable zombies to the point where they reach their doom, while you make a run for it and hope that you yourself will not be trapped. The winning system can be either a last man standing, who survives the longest, or who had the least deaths. I would suggest a set group of swords and gun, giving everyone fair advantage, using the guns or sword to shoot trigger switches, or using the swords for knock back until your door opens. A nice way to spicen the game up would to have a few status type zombies randomly appear instead of the typical bland stunner.

And these are my suggestions, I realize there is a lot to read but I feel they are incredibly worth reading and I hope many will comment and offer any suggestions.