Abyss is basically a gear check and seasoned with luck/rng and little bit of int lol.. Don't push yourself too much with abyss or you'll drown real hard, slowly improve your gears, defeating abyss is not juat about the units, it is mostly on gears and strategy, check the gears and stats of those guys on youtube, compare it with yours, if they are the same then it's just eng messing up with you, if not the same, then go focus on hunts, raids the normal and new one, improve gears then face the abyss again when you are more ready

edit: managed to beat it last night... turns out all videos ive watched mentioning ads need to be lower hp than main spider was my problem.

i took that to heart rather than just killing the ads FIRST.  i had lost previously because i was focusing on the hp bars of the ads thinking it was less than the main spider and that'd cost me the loss as they healed the main spider.

so instead, i attempted to kill the ads ASAP. and fight ended sooooooo much easier!

hope this helps someone else. 

...thanks also Louche for replying!

Actually SSB was a heaven sent for me when I was stuck at floor 82. My team where A.Momo, A.Ras, Angelica, SSB