This could probably be split into two separate threads, but the ideas tie closely into each other. Basically, new stage hazards, and an example boss that uses them.

Hazards
Basically, I noticed that a lot of the difficulty in the game comes not with the monsters themselves, but with the placement of stage hazards and avoiding damage from them. For example, being confined to a 3x3 ring surrounded by fire or spikes with a few ranged enemies is a lot more difficult than fighting a dozen of the same enemy in an open area, because there is more room for error and it would be more forgiveable in that case. I believe the same holds true for the recent Almire prestige, because even though the combinations of enemies can be downright brutal at times (healing, revive, burst damage), I find that its only really difficult if you cannot maneuver. Therefore, it would make sense to introduce new/more stage hazards to the game to make things interesting.

The main idea I had was for a T3 difficulty boss, similar to Vanaduke, but with a different setting. I noticed shock had not been used in any boss areas, so my idea is basically an electric/magnetism themed dungeon. There is a lot of potential here, but the main mechanic would be based on polarity. Polarity is Red or Blue (positive and negative, of course). Some specific ideas:

• Different "charging panels" that set your polarity to what it displays
• Tesla coils that slow charge up, emit lightning at anything within a 5 square radius that has the opposite polarity, alternating its polarity each shot
• Magnetic flooring that either increases your speed if you match polarity, or slows you down if you oppose it
• Wall panels or standing rods that attract or repel you depending on your polarity
• Doors/barriers that may only be crossed if you match polarity

There is probably enough depth in those alone, but you get the idea for the potential situations you could create. Note that for stage hazards, there is an effect if the polarity matches, as well as if it differs. For enemies, the effect is only present if it differs.

Enemies
Gremlin Bomber

• Like a Gremlin Demo, but also releases the occasional mine that homes in on opposite polarity, or just stays put
• These bombs are like the elemental shock ones that players can make, and leave an area on the floor

Gremlin Shocktrooper

• Similar to a Thwacker, but their damage is increased if your polarity differs
• Attacks also release a small, immediate burst of AoE shock damage if they hit

Shock Puppy Ultra

• Shoots two waves of 5 bullets at the same time, one for each polarity
• Basically the shots expand in a pattern mirrored to each other
• Bullets home in slightly if polarity differs

Dungeon
An example of a dungeon could introduce a new statue-like object called a battery, which when placed, powers up electric devices. This is very similar to a statue, but it could do different things. For example, players might have to adopt a red polarity to go through a barrier into a blue room, which makes things more difficult. They retrieve a battery, which allows them to power a shuttered door so that they can proceed. Another example would be to remove a battery that powers a conveyor belt (which would have pushed players into spikes/electricity), and place it instead in a turret, which would then proceed to shoot at enemies.

Batteries should be moveable, but perhaps there would be special spots that "lock" once placed, preventing it from being moved. Good level design should prevent this, however. Another dungeon element that comes to mind is the lasers used by the Roarmulus Twins. Technically they're used in the boss fight only (and as a gate in the final level, but that's a moot point). You could expand their use and for example, place a battery to power them on, and place mirrors (similar to statues) to reflect the laser, creating possible puzzles, stage hazards, and give the players the ability to clear rooms, as needed.

Finally, tubes! These can be polarized to require making choices, or simply left neutral. If a player enters the tube, they shoot through it to the other side (a la Mario). If it would fit the theme better, they could be teleporters. In any case, these would lead the way to create a disjointed, fragmented level. As the levels themselves are fragmented from one another, this builds on the theme, and can create complex levels in which navigation and solving puzzles becomes more difficult, even if a player has a full view of the area. If the puzzle is too difficult, perhaps allow a split in the path to a combat area, or an energy door to bypass it. While 3 CE is not a lot, presenting 3 puzzles could allow the lazy player to quickly bypass them - for a cost.

Boss
The boss could be some form of Gremlin mad scientist or perhaps an angered construct (although with the Roarmulus Twins, this creates an overlap in bosses). The stage gimmick could include any of the various ideas presented above. Perhaps the room's floor changes as the fight progresses. Maybe it has a laser as the bottom, with mirrors on a conveyor belt. You get the idea. The key here is that the boss itself is based around polarity. I think the optimal balance for the boss would be to have 3-5 attack patterns, with a different effect depending again on polarity. This gives players a choice in the boss lobby do you want to make the red or the blue attacks more difficult?

Some attacks could include:

• EMP Bomb - The boss shoots or throws a bomb at a high velocity at a target (preferably closer to more knights). It deals a heavy amount of damage on a direct hit (similar to a Lumber), and emits an immediate AoE around the size of a 2* bomb.
  • Red polarity: Applies strong stun
  • Blue polarity: Applies strong shock
• Polarity Switch - The boss emits a wave of magnetism throughout the room, making each knight's polarity the opposite of what it was. Note that depending on stage hazards, this could have devastating effects. If the boss has phases, he should use this ability between them, and once the second phase is reached, use it again every 30 seconds or so.
• Energy Spike - Smashes a single knight for massive damage, inverting their polarity
• Missile Barrage - Shoots a wave of 9 missles across the room. The first 5 should be aimed similar to a turret, with the last 4 being aimed at the gaps between the first five. This attack does not home, but with stage hazards, it could be a very difficult to dodge.
  • Red polarity: Applies strong fire
  • Blue polarity: Applies strong stun
• Barrier - The boss places themselves in a pink or blue barrier (similar to a Mender's, but larger) and can only be attacked by knights of the correct polarity. It does not last long, but the boss could place multiple ones in succession as part of an attack.

Phew, that was a mouthful, but hopefully you can see the potential here. :)