The Jailer's Gauntlet: Layer 4

Layer 4 completed on a 232 Beast Master Hunter, with spectral crab pet in tenacity, Animal Companion talent, on the first attempt.
Animas order of importance:
"Chelonian Crest", "Death's Rest" , "Craven Strategem", "Piercing Scope", "Zovaal's Versatile Vittles", "Deadeye Satchel", "Bone Barbs"

Here is my strategy:
Look for the Animas called "Chelonian Crest", which increases the duration of Aspect of the Turtle and allows you to use all abilities while protected by it. "Death's Rest" Anima resets the cooldown on all aspects. If you have either 2 stacks of "Chelonian Crest" (increasing Aspect of the Turtle by a total of 400%, or an Anima called "Craven Strategem" (which reduces your Feign Death by 15 seconds) you will have unlimited Aspect of the Turtle, making you completely invincible for every fight. Simply cast Aspect of the Turtle, followed by Feign Death, which will reset all aspects. Once Aspect of the Turtle expires, or a second or 2 before, recast Aspect of the Turtle, followed by another Feign Death. Rinse and repeat for the whole fight. I try to recast Aspect of the Turtle a second or 2 before it expires to make sure there is zero time when I am not protected. Super easy, even if your pet dies. You will be able to rez him while under the Aspect of the Turtle, so no big deal there. To make the fights quicker, you are also looking for an Anima called "Piercing Scope" which increases all damage to mobs by 15% while they are marked by Hunters Mark. Another helpful Anima is "Zovaal's Versatile Vittles" which increases your pets health, damage, and size. "Deadeye Satchel" (kill shot has a 25% chance to instantly kill a target below 20% health) is a good choice if none of the forementioned Animas are avaliable. "Bone Barbs" will also be helpful, but is less important than "Chelonian Crest" and "Craven Strategem".
Buffs for your pet are the most important Animas after "Chelonian Crest" and "Craven Strategem".
As long as you are under the protection of Aspect of the Turtle constantly, and have "Chelonian Crest" and "Craven Strategem" Animas, you will be invincible and will have use of all of your abilities. The only real issue that I had was keeping an eye on the timers/ cooldowns.

Completed the entire run on the first try, 1 death, due to a misclick on Aspect of the Turtle, and it took roughly 90 minutes, and due to some luck I received the mount on this first attempt.
I am sure there are other strategies, but this one worked extremely well for me. Good Luck!

@Woodymakespizza I think it's meant to be colossal for a mawrat :D

we easily pugged layer 3 but couldnt finish 4 , its getting way harder there