Suggestion: an option to have the womb/utero/scarred womb bosses show up in Boss Rush, to keep it in line with how Fiend Folio adds chapter 4 bosses to boss rush

add more bosses

Not so much a suggestion as feedback and review for a bunch of these bosses (except for maybe 2 of these), so here you go (sorry for the wall of text):

• Sparky and Bart are really easy if you pay attention, probably the easiest in the mod. The closest thing that's threatening about Bart is their dash attack while they're ignited which can cut the room in half because of the little fires left behind, though for the most part it's still slightly easier than their first phase because they shoot little fires and spawn dips more than they do the dash attack.
  
• Radical Rat could have their HP bumped down a smidge, the layout of the arena and their attacks (such as when they hide under their bin) do make landing all your shots harder. He's comparable to Little Horn in that way, but they actually have the same amount of HP funnily enough. Also their unique item, Rat Bombs, should give +5 bombs like other bomb upgrades.
  
• Chapter 1 bosses as a whole are pretty easy and more comparable to vanilla bosses in difficulty, which is almost refreshing in comparison to how every single one of Fiend Folio's chapter 1 bosses have a lot more going on in their attacks (not that that's a bad thing).
  
• Scat Man's scat balls feel like they have a lot of HP (at close-to base stats anyway) but I think that's the point, since Scat Man can usually clear them for you when they use their detonation attack or run them over with their big poop ball.
  
• Mirage probably has the least fair attacks in the entire mod, particularly their bite attack. The thing about other enemies that do "lunging" attacks (like Gnawful and Drooler from Fiend Folio) is that they tend to "overshoot" Isaac with their lunges, which gives enough room to sidestep them. Mirage's bite attacks are way too quick to do this, you have to basically be across the room WAY in advance in order to ensure you don't get hit, and it's not real fun.
  
• Mozzie I found I sometimes get cornered into a wall and get hit a lot when she's chasing me if I have low speed, but I'm sure just avoiding hugging the wall if possible helps when she's approaching you.
  
• Some of Dust Devil's attacks are pretty easy to cheese, like her swooping attack where you can just stand near the top of the room, but others are pretty tough, like her whirlwind attack and sandstorm attack. For the sandstorm attack I found it's easier to dodge Devil's charges if you use the wind to your advantage to get out of the way faster, but ironically moving closer to the source of the wind also make you more likely to get blindsided by a pattern of dust bullets you didn't have enough time to get out of the way from.
  
• Wallmonger Mournmerus is a pretty intense fight, probably my favorite in the mod in terms of presentation. I felt a lot of their attacks rely really heavily on memorization, fighting them the first time you're bound to get hit by an attack you couldn't avoid because you were preemptively standing in the wrong spot (like the alternating walls of Shady-colored bullets. Or the classic Nuclear Throne ♥♥♥♥-off mega laser)
  
• Duke Bloat is evil. I will never forgive Akio for this /j.

Don't know what else to say about the rest of the bosses (yet?)

Originally posted by Khakis:

Not so much a suggestion as feedback and review for a bunch of these bosses (except for maybe 2 of these), so here you go (sorry for the wall of text):

• Sparky and Bart are really easy if you pay attention, probably the easiest in the mod. The closest thing that's threatening about Bart is their dash attack while they're ignited which can cut the room in half because of the little fires left behind, though for the most part it's still slightly easier than their first phase because they shoot little fires and spawn dips more than they do the dash attack.
  
• Radical Rat could have their HP bumped down a smidge, the layout of the arena and their attacks (such as when they hide under their bin) do make landing all your shots harder. He's comparable to Little Horn in that way, but they actually have the same amount of HP funnily enough. Also their unique item, Rat Bombs, should give +5 bombs like other bomb upgrades.
  
• Chapter 1 bosses as a whole are pretty easy and more comparable to vanilla bosses in difficulty, which is almost refreshing in comparison to how every single one of Fiend Folio's chapter 1 bosses have a lot more going on in their attacks (not that that's a bad thing).
  
• Scat Man's scat balls feel like they have a lot of HP (at close-to base stats anyway) but I think that's the point, since Scat Man can usually clear them for you when they use their detonation attack or run them over with their big poop ball.
  
• Mirage probably has the least fair attacks in the entire mod, particularly their bite attack. The thing about other enemies that do "lunging" attacks (like Gnawful and Drooler from Fiend Folio) is that they tend to "overshoot" Isaac with their lunges, which gives enough room to sidestep them. Mirage's bite attacks are way too quick to do this, you have to basically be across the room WAY in advance in order to ensure you don't get hit, and it's not real fun.
  
• Mozzie I found I sometimes get cornered into a wall and get hit a lot when she's chasing me if I have low speed, but I'm sure just avoiding hugging the wall if possible helps when she's approaching you.
  
• Some of Dust Devil's attacks are pretty easy to cheese, like her swooping attack where you can just stand near the top of the room, but others are pretty tough, like her whirlwind attack and sandstorm attack. For the sandstorm attack I found it's easier to dodge Devil's charges if you use the wind to your advantage to get out of the way faster, but ironically moving closer to the source of the wind also make you more likely to get blindsided by a pattern of dust bullets you didn't have enough time to get out of the way from.
  
• Wallmonger Mournmerus is a pretty intense fight, probably my favorite in the mod in terms of presentation. I felt a lot of their attacks rely really heavily on memorization, fighting them the first time you're bound to get hit by an attack you couldn't avoid because you were preemptively standing in the wrong spot (like the alternating walls of Shady-colored bullets. Or the classic Nuclear Throne ♥♥♥♥-off mega laser)
  
• Duke Bloat is evil. I will never forgive Akio for this /j.

Don't know what else to say about the rest of the bosses (yet?)

Rat Bombs are unfinished and unobtainable so Rad Rat doesn't have it as a unique drop yet.
For Mirage's lunge attack, you really just need to circle around them and that makes it a lot easier.

Originally posted by PixelPlz:

Rat Bombs are unfinished and unobtainable so Rad Rat doesn't have it as a unique drop yet.
For Mirage's lunge attack, you really just need to circle around them and that makes it a lot easier.

Oh okay, that explains why the item was labeled as hidden, I thought it was because it was a exclusive boss drop and I hadn't encountered rad rat in a normal run yet to know better.

dust devil slowly following you while doing her spinning attack feels a bit too oppressive. you can get backed into a corner and forced to take damage. itd be better if she stayed in the middle of the room.

feel like dust devils sandstorm could be a bit weaker cuz if you dont run in the direction its going in you cant dodge most things

also WAS the wall guy in gehenna based off of wallmonger from gungeon

also i do feel like mirages dash should like overshoot a bit like that other guy said

I haven't installed the mod yet, can you configure what bosses can spawn and which ones can't? if not, that's my suggestion.

Originally posted by anoceansoul:

I haven't installed the mod yet, can you configure what bosses can spawn and which ones can't? if not, that's my suggestion.

no

This mod is amazing, I love the creativity and references behind the bosses.

This is a minor suggestion, but I believe Mournmurus´ design could use some more details. Comparing it to the Wallmonger from Enter the gungeon or the walls from improved backdrops and visuals, it looks a little bland. Maybe you could add some spikes, bone fragments or chains to make its design more visually striking.

This is of course a very minor suggestion but it could make the boss visually more interesting. Mechanically and conceptually it is already a masterpiece, plus extra points for adding a boss to the small gehena´s roster.

For Future Mods,
Would you ever consider doing the equivalent of a "Booster Pack" format, that focuses on adding bite-sized stuff like new items, bosses, enemies, tweaks, ETC?

Originally posted by Sleepy-Keyzer:

For Future Mods,
Would you ever consider doing the equivalent of a "Booster Pack" format, that focuses on adding bite-sized stuff like new items, bosses, enemies, tweaks, ETC?

this is a boss mod

I'm glad there's a suggestions/feedback place here so i can throw my peace out, something i said on a youtube showcase of the mod is that some of the boss's death animations feel...just a tiny bit too short or missing something overall, there isn't really any "oh no im dying", it's difficult to explain but some of them feel abrupt in jumping between fight to animation along with some i think missing those little "gib" particles that spawn when something like Monstro is dying

Im unsure of the state of some of them being finished or not but something to take into consideration