Well, that certainly was interesting.

Difficulty

In my opinion, this was harder than LoA, not by a whole lot, but still harder. I find the difficulty perfect.

Level Design

First floor: The clockwork-tunnel-like areas had land arround them, I liked this, gave a new feel even though it was a small change. The pre-made rooms were well done, they has more room than LoA, meaning gunners wont have as much trouble. Though the poisoned oil spawning at the beggining of waves seemed a little bit much, the nuclear slimes provide PLENTY enough of that..

Second floor: This felt alot like the IMF, a nice factory feel to it. there was LOTS of fire here, though maybe some of it should be replaced with fire that causes poison? Rooms are a little more tightly packed, but not too much to give gunners trouble (at least me). The final room was nice, the switches and fire were placed nicely and the enemies spawn in the right amounts to prevent crowding but still be difficult, and, of course, the minibosses.

New Enemies

Nuclear Lichen: A lichen with all the attacks and both statuses of oilers and toxigels, with a dash attack leaving a trail toxic oil. Gotta love'em. Could maybe use a SLIGHT decrease in the oil they lay.

Nuclear Polyps: They shoot like regular polyps (do the thorns cause fire? they have the same texture as the poison ones.), as well as surround themselves with toxic oil, and spawn the lichens. They seem fine as is.

Nuclear Baron: Giant nuclear lichen, not much else I noticed. Needs to be a bit more complicated.

Gremlin Boss (what was his name again?): This guy was virtually Itentical to Razwog, again, needs to be a little more complicated.

Other

Toxic Oil: Works well, but would it be possible to make it not affect sheilds? It is a bit annoying shielding an attack and becoming locked in place.

Flamethrower Blocks: Indestructable Red Rovers. Lord save us. A slight range decrease would make them seem a little less cheap.

Mortafires: I like how these were put in free content, nice for F2P player to be able to fight them without buying OCH (or trading, when it is tradeable).

Overall

Nice level design, nice new enemies and enviromental hazards, and a change from all end-game being undead. I also like how it encourages the use of Dragon scale armour, since it isnt used for more than costumes very often right now. The minibosses were a bit of a letdown though, and there is SO MUCH going on, your FPS is more than halved (Though I was playing from a laptop, which doesn't run as well as my desktop). I'd give it a 8.5/10., Good, but need a few tweaks.

Please excuse any bad grammer/spelling, was typing on a tablet.