Art
On one hand, I like it, it's got a golden era of comics feel to it, it sort of reminds me of Johnny Quest, and the inking is very professional. That being said there is room for improvement. Firstly is that your eyes are generally slightly too big for your heads, and you don't really convey well a sense of depth on the face. It feels more like you've painted features on an egg. Which brings me to my next issue with the way you draw faces, you don't have alot of variation in your design, this one has lipstick, while that one's blonde, but really their facial features are nearly identical. Finally, there is an issue with consistancy. If you look closely (as I feel I must to give a decent critique) you'll notice that from panel to panel things like proportionality of eyes to head, nose length and depth of cheekbones are all over the place. As a reader I never really noticed it, but I was AWARE of it. I could tell there was something off putting that seperated your art from being on par with golden age comics, even though, superfically, it maintained alot of the same principles. Thats just my critique on the faces too, when we get to body shots and action sequences, I have new issues. You need to get a better feel for weight. You need to exaggerate where the weight is in each panel more than they might actually need it. Currently it seems more like you're posing action figures and drawing them. That is to say, they're very stiff. Remember you don't have motion to help convey action you only have a snapshot. Exaggerate your motion and it will look more natural. Give proportionate center of gravity and weight to limbs, if someone is hanging their head in thier hands it's going to effect their shoulders, their head isn't just lower. The consistancy issue comes back when I talk about backgrounds too. In one panel there will be a crack in the wall where bricks show on the right side of the person, in the next panel the person will have clearly not moved, but the crack will be on the left side of the person. In one panel there will be a statue by the door, later, same door, no statue. Here a character is wearing lipstick, one strip later lipstick's gone, next strip it's back. Theres alot good about your art, but theres alot that needs to be fixed, and theres alot that looks like you don't even need to improve to fix, but that you're just being lazy, or you're rushing. Infact, yours is one of the only comics I've seen where the art seems to get worse in later pages. I don't know if you're just being lazy or if it's because you lost your inker and he cleaned up alot of the minor errors for you in the past, but if you compare the art from book 7 to the art from book 12, theres a huge gap. Book 7 was very crisp the inking was fantastic and added depth where it needed to be and aided the anatomy of the art, and in book 12 it's entirely the opposite.
Writing
I used to do alot of excel lists at work, and so to help me from falling asleep in the middle of them I found some old timey radio shows on line, specifically old "The Shadow" programs. They had their charm, but being a radio program you ended up with alot of dialogue like this:
Evil Scientist Dr. Carlson: "I'm climbing the tower to the towns water supply! After I poison it my plan will be complete"
Shadow: "But I am right behind you Dr. Carlson. I'll stop you long before you reach the top."
Evil Scientist Dr. Carlson: "I'm already at the top, Shadow. Boy. It's windy up here! Now just to open the hatch to the water tower."
*Police sirens in background*
Shadow: "I'm at the top too Carlson! Your time is up!"
Evil Scientist Dr. Carlson: "You're too late Shadow! The hatch is open! The city will soon be dead!"
Shadow: "I've closed the hatch again Carlson. Its no use. You'd better climb down and turn yourself in."
Evil Scientist Dr. Carlson: "You'll never take me alive Shadow! I'll push you off the tower and then poison the water anyway!"
Shadow: "You'll never find me Carlson! I've clouded your vison to my location. You'll fall off the water tower first. It's too windy, just turn yourself in."
Evil Scientist Dr. Carlson: "Oh No! The wind blew me off the water tower! Ahhhhhhhhh"
Shadow: "Well Dr. Carlson. I guess the nightmare is finally over."
I shit you not, thats how the dialogue was. You're dialogue is often like this as well. Not usually as ridiculous but theres alot of characters announcing their actions while they're performing them. Theres alot of characters announcing their actions and intentions. For example "Every fiber of my body is being penetrated by it's dark magic! It-It's changing me!" Who says this when dark magic is penetrating every fiber of their body? If you hold your hand over a lighter you're not going to say, "the fire from my lighter is burning the flesh on my hand." You're going to say "holy crap, goddamnit ow!" If your intentionality is to "sound like" this golden age pulp fiction then you are there, but there is a reason popular culture left these things behind. They sound unnatural, like actors performing a play for children. One of the key principles of fiction writing is show, don't tell. Now, sometimes this works in your favor. Sometimes the stiff radio-show type dialogue really hits home and is funny, or dramatic or helps establish a certain mood. But you have every character talking the same way all the time, with this same sort of dialogue. Finally when you have the same character say "It's time to rock and roll!" and " By the awesome avatar of the ashboratep!" Well, one of those is a little out of character. I'll let you decide which one.
Now onto the story... I have no freaking Idea what the hell is going on and why. I understand you started at the point you started at because you felt the first four chapters just weren't as strong/were in a different format and you didn't really do any extra work, but you're just plopping us down with already developed characters in an already established universe without any introduction. So it takes several pages including action pages that lose there suspense because we don't know why anything's happening before your readers get their footing. Now, Let me bring up the Johnny Quest comparison again, because just like Johnny Quest, I don't care about these characters. They don't have any personality, so it's hard to feel for their dilemma. They're broad characterizations, they don't seem like actual people. The bad guys are too bad and the good guys are too good. Plus, every time the characters are in a bit of a jam you Deus-ex-machina them out of it. Giant bugs are about to devour them; cowboys come along and save them. They go to a dimension where everyone wants to kill them; future alien wife appears out of no where and shows them how to escape unharmed. Giant bugs about to rip apart the very fabric of space/time destroying all existance; whichthorn suddenly and without clear reason "unlocks his true power" and banishes them to their original dimension, even though they some how got out of that dimension in the first place, but whatever everything's fine now. The thing is, you don't just do this with external conflicts but internal conflicts as well. You've been building the "Whichthorn can't let his dead wife go" storyline up since the beginning of the story then out of the blue you have
this! I dropped an audible "WTF!" "Well I just beat the Archmorg, I don't care about my dead wife anymore." and then the Archmorg is like "I'll get you Inspector Gadget! I'll get you yet!"
Production:
This is where you excel the most. The style of speech and throught bubbles you use are perfect for the format. The font you've chosen for the text, the title, the sound effects everything is exactly what it should be. And the camera angles you use ar dynamic, your panel layout is clear and it varies from page to page in order to best tell the story. I can not fault the production of this comic in any way shape or form. Everything is done to a "T" without the slightest issue. I did catch a grammatical error here and there, but they were miniscule, and I was looking for them, the average reader wont bat an eyelash.
All and all I think you've produced a strong comic that established and maintains the feel of golden-age pulp comics, but unfortunately it doesn't overcome some of the glaring writing issues that plauged pulp comics in their hayday and marked the reason they've become a thing of the past. Nor does it seem self aware of any of these issues, as a contemporary writer should. While the art is often strong it is also inconsistant which gives a weaker overall impression of a page than one might have otherwise.