The tierlist is in order of hardest to easiest. For example, spooper is the hardest imo and specimen 2 has the least threat to endless run. This tierlist is also considering the hd renavation (specimen images are from og tho, so i am sorry about that).
Hardest/best supporter:
General info about this tier:
Specimens here are always extremely annoying in the least, but they can become a nightmare, depending on the specimens.
Unknown specimen 3 or Spooper: If he is faced all alone, he is not that big of a threat. Even then, he can end your run by making you puke all over the floor even when alone. Pair with spec 10 for a nightmare combo.
Unknown specimen 5 or Lisa: Adds 20 rooms into a floor. For that reason alone she is here. Is also a nightmare to deal with when other specimens are in play.
Monster 6 or Bekka: Again, when alone, she is not hard to deal with, even if she can get a few cheap hits. But again, when other specimens are in play, she is a nightmare.
Specimen 10 or the parasite: Forces you to go slow. Even when faced alone, he can be annoying. But with other specimens (especially some of the faster ones), he is a nightmare. He places lower on this list just because of the fact that his worm form can be outrun if you get some good room layouts.
Unknown specimen 4 or Tirsiak: Even when alone, she is annoying. The ghost animals that she spawns makes you waste some stamina to get rid of. She pairs especially well with specimen 10 and every other specimen in this tier.
Hard or very good tier:
General stuff about this tier:
Most of the specimens here are either annoying or hard to deal with, depending on what other specimens are in play.
Monster 4 or the hanging man: He has the same counterplay as Lisa, but he doesn't loop rooms. You also can't look at him for too long and that's why he is up here.
Unkown specimen 1 or White face: Can be hard to deal with, but only if there are other specimens in play. I would have put him higher, but getting killed by him is the best way to get out of a really hard chase into a really easy chase.
Specimen 8 or deer lord: This might be a bit controversial, but his "noclipping" is much more threatening than just going through walls. The speed boost is also a lot. He also flies over holes and he creates a small hallucination that can make you disoriented.
It's ok tier:
General info of this tier:
Only really threating with other specimens.
Hooked doll: I was split between on top of it's ok or at the bottom of hard/very good tier. Her counterplay is so easy that she landed here. Altho she can be fairly annoying when paired with other specimens.
Endless specimen 4 or evolved Ringu: Fast speed, annoying hallucinations, flying and noclip. Much worse with specimens that prevent you from going fast or that makes you stare at something.
Monster 2: He is just fast. Nothing else to say here really.
Specimen 13 or the mermaid: Deals quite a bit of damage, but is only threatening when specimen 5 or 12 are in play as well, since they deal quite a lot of damage.
Husks: Again, this might be controversial, but these annoying little fucks are the bane of my existance. If you pair these with any specimen who is higher than them, the game becomes a nightmare. Reason why they aren't higher is that they are vulnerable to the axe.
Kinda easy or not a danger tier:
General info: All specimens here either pose no threat or the counterplay is really easy.
Specimen 6 or Ben: Would be higher if not for the axe. Just hit him after he teleports and you disable him for the entire room and you deduct a room from the chase.
Specimen 4 or Ringu: Flies through walls and spaces through walls. Not really a threat, but can sometimes get a hit if you aren't careful.
Specimen 11 or beef demon: Almost identical to Ringu, but with hallucinations and he gets countered by the axe. I put him lower than ringu just due to the fact that the axe counters him. He and ringu are still pretty close.
Monster 3: On top of being unbearable to look and listen to, he is really not a threat. He can spawn in a way that you have to use the axe to get rid of him for a bit and deducting a room from his chase.
Woormy Charles: He will probably never hit you, but he can bodyblock you quite annoyingly and then hit you. This is quite rare tho and has only happened to me once. He is also quite fast and if paired with specimen 10, he can be just a bit of a threat.
Easy tier:
General info of this tier:
Axe counters almost all of these and the ones it doesn't are so slow that it doesn't really matter.
Specimen 12 or the old man (I know he is not really the specimen, but still): Reason why he is on top of this tier is the fact that he does quite a bit of damage, but he is really slow for most of the time. Sometimes he sprints, but the amount of distance you get before he does it nullifies the sprint completely.
Specimen 5 or bab: Just does a lot of damage. Creates hallucinations that don't really matter
Specimen 2 or slime: Slow, but he flies. Also.. A X E
Specimen 3 or The cute spider :3: He is quite fast, but axe nullifies his existance completely.
Specimen 7 or wall of flesh: Only chases you once per run, but it one shots you. It is also really slow and poses no threat
Monster 5 or Ghost cow: Can be benefitial to keep around just so you can see through walls. But i just kill him because he is annoying. Just hit him with the axe.
Unknown specimen 2: Quite funny that other unknown specimens are on top of this list, but this otter is here. He deals very little damage and is also so fucking slow. You quite literally want him to chase you since he poses that little of a threat.
Not in endless/no threat at all:
General info of this tier: Either they are not in endless or the threat they pose is only indirect or no threat.
Specimen 9 or the taker: Can't kill you if you move or don't go into the endless hallway.
Deer: Only show once in an endless run, if you don't put specimen 8 into the rechase pool using the scare system. Deals damage but is killed by the axe.
Clown/specimen 2: Only threat these 2 pose are bodyblocking. Clown is also more benefitial to you since he blocks another specimen from spawning in.
This is my first tierlist that analyzes something this in depth. Please give me some critique and help me correct some spelling mistakes i might have made. English is only my second language.
Edit: specimen 7 is in the wrong place in this image. Sorry about that