But...in all seriousness...
I'm open to ideas for a new layer of the Abyss. My biggest requirement is that it has to be so hard that everyone fusses that it's unbeatable and must
be downgraded or you'll never go there again.
Then, one year later, someone conquers it and we need a new layer. It's already happened. Search this board.
I'm quite surprised no one has commented on this yet, at least publically, so I decided I'll put my two cents in. I'd still personally like to see two new layers, but if you're set on only one, I'd still be grateful. I'm mostly going to add my perspective on what kind of mechanics I'd like to see inside as I've already given my opinion on specific monsters previously.
So what I'd like to see, is a slow down on the ground, kind of like how abyss 2 sped you up some and made it slippery, it'd be interesting to see how an effect of a permanent 75% or so movement rate would be. Making it so that creatures cannot really be outrun. And if you're looking to be extra nasty give 25%-50% of the monsters inside the stupidly annoying I'm going to run in front of you and get you trapped AI basically making the area un-runnable.
And I know I may live to regret this, but I'm going to go ahead and give specific details on how to make an area Garr-proof, and what I mean by this is that I will not be able to run into an area by myself, gather up all the monsters and use my Lava Cloak to kill the vast majority. This is not saying I won't still try, and still may be able to hold most things while the group lures them off of me, (But I'll give a couple ways of killing me during this process as well)
So there are 3 main ways I can think of to counteract the damage the lava cloak does. Feralers, Troiluser, and things with the Skeletal AI. I suggest all three of these types of monster be put into Abyss 3. I'll explain each type briefly and how it counteracts the cloak. Feralers essentially will stay in my vicinity, but will be constantly be circling and not be bumping into many monsters on fire. Troilusers are obvious. They heal back the health lost before the cloak gets a chance to kill them. And Those with the Skeletal AI will take very little damage from the cloak as they hardly move at all, and will only spread the initial burst of fire rather than to keep spreading it over time.
Next I'll explain the best ways of killing me while I am currently girdling. There are two main ways I can think of. First lots and lots of projectile damage, it all adds up and eventually takes it's toll. But this is preventable as I can remove and re-put on the girdle quickly and restart the process. What I would suggest is earthquakes. Not the kind that damage you because those are no fun for anyone, but just like the Sezuma Yorilla make. If these are happening frequently enough, (whether it be from a monster, or just an area effect) eventually one will happen during the time the the girdle expires and I will die, and then what usually happens is that everyone else dies too. So win for the Abyss. What I would like to see though if this were to happen, and actually would like to see in any case even if not in Abyss 3, would be some way to make it so that when completely surrounded by monsters during a quake to stay in the same place at the end of the quake rather than porting to the most recent entry point on the snell. I think I understand why it happens. (there's not enough room) But if there were some way to fix this I'd be greatly appreciative as it can be quite annoying.