Hiya!
(a bit of a pre-amble; if you want to jump straight to it, scroll on down to "So I fixed it")
We never got into Planescape. A couple "core things" annoyed us to no end. First, the "blood wars". No thanks. Second, "its the center of the multiverse, so there!". Double No on that. Third, "plane-speak" for flavour? Oh my gawds! It was
horrible. Always made us picture Dick Van Dyke as a chimney sweep and a bad accent. Lastly was..."the Lady of Pain". We all hated the concept.
Now, all of those I did "nix". The Blood War was re-imagined as something that Devils and Demons do to "practice". Neither side was really trying to "win" so much as just revel in the glory of battle. Think of it like two drunken Scotsmen getting into a friendly bout of fisticuffs "just for fun".
There is no "center of the multiverse". What Sigil became was it's own unique plane of existence where it had 'areas' that touched both Sigil and whatever 'normal' plane it was. So if you went to they Abyss via Sigil, you were actually in a sort of demi-plane where Sigil and a part of the actual Abyss is.
Plane Speak? We just tried to ignore it. No fixing that.
And finally, the Lady of Pain. I *absolutely loathed* the idea that TSR just up and decided that the most powerful 'creature' in the universe was
always going to be more powerful than anything I, as DM, created/decided. Yes, I know I could always ignore it. The point is that TSR put in a "ringer" and then specifically and absolutely decided something. "Odin has 400hp" in the 1e D&DG. Everyone knows HP's are something a DM can change. So that's fine. "The Lady of Pain can not be killed"...that's not. That was, to me, like saying "Odin has infinite hp". You can't really adjust "infinite" up or down. I don't know...it just really
REALLY bugged me.
So I fixed it. I decided that the Lady of Pain wasn't a conscious entity. She was a semi-physical 'multi-dimensional' construct. She was also a sort of "prison" for any god-like entity that tried to step/enter into Sigil. When Sigil first sprang into being, the Lady of Pain was just an abstract 'anchor' to the plane due to it's more or less direct interaction with the other planes. Of course, it took all of 3 seconds for a god to try and see what this 'new and unique plane' was all about. And...SURPRISE! That god was instantly transferred into the 'construct' of the Lady of Pain. While wearing the Lady of Pain suit, the god found it could wander around, watch, and even exert some of it's power to kill, heal, or whatever...but in a MUCH more limited way (pretty much 'local only'). What was worse, was that the god couldn't communicate
in any way while 'in' the LoP suit. Perhaps even more upsetting was that the god would get 'kicked out' of the vessel at seemingly random times. After a time, all the gods in existence knew that it was more or less pointless to try and mess with the Lady of Pain simply because even if she was 'destroyed' (and she was on a few occasions...probably when it was some demi-god driving), the next moment the vessel would be reformed somewhere in Sigil.
And thus, in my 2e campaign I had waaaaay back when, the Lady Of Pain wasn't a "person", she was just a meat-suit for deities of the multiverse to pop into and sort of 'get away from it all' for a little while.
Never had anyone try and mess with her simply because they knew that it was some god/dess. Maybe a bad one, maybe a good one. The point being that the god/dess 'inside' the LoP would know them.
Stat wise? I'd probably just have given her some range of stats and rolled every time the PC's decided to take a pop-shot at her. Maybe she'd have 150hp and AC -2....or maybe she'd have 1,000hp and AC -30. Maybe she'd be able to do 6d6 lightning bolts, or maybe she'd be able to shoot 6d6 beams of Disintegration. Who knows? ...and that was the entire point...
^_^
Paul L. Ming