In the Halls of Vaught in the Betrayal of Harrogath quest, there are four doors and Nihlathak is in one of them randomly. I read somewhere that there is a particular artwork on the door to his room that indicates which one he is in, but I can't find that reference anywhere. Anyone know anything about this?

https://maxroll.gg/d2/meta/nihlathak-farming-guide

Look for the red eyes on the walls.

It's a roguelite. The levels are somewhat randomly generated. No one can tell you where he is.

It has been there since the start. The screenshots in the link unfortunately show D2:R, but I remember farming him ages ago and using the walls to quickly find him.

I've found you a video from the original which clearly shows you what you have to do:
https://www.youtube.com/watch?v=QBitkTEB0A8

Took like 5 minutes to find. It's much less obvious with the vanilla graphics than in D2:R. You need to look at a specific segment of the wall, depending on the direction you're checking.

But yes, Arcane Sanctuary has no way to tell. Yes, but many locations still follow certain rules when being generated, especially with waypoint placement. Look at the video I linked, the guy goes over the 3 basic layouts you can get of the dungeon before the boss.

And in Nihlathak's case, you can always tell exactly thanks to the visual hint.

Where in a level, no. But he will always appear in the same room/level.

From what i remember, the levels weren't that huge or complex in the past, although mods would increase the size several fold the base game it shouldn't be too hard.

Regardless, when in doubt, search all the rooms.

It's not that big an issue. As I said, the button for your quest panel displays as an effective warning before you meet him. (In the Arcane Sanctuary, the quest button won't display until you have directly seen the Summoner.)

BTW, I may be confused, but I thought the basic definition of a roguelite wasn't procedural generation, but whether you could save to prevent character death. Now, of course, you are right. In Diablo II, you can't save at any exact point you want. In that way, it is a roguelite. In particular, if you're not playing a hardcore character, I'd say normal difficulty is "very lite" in that respect. (And in recent versions, nightmare and hell difficulties are "liter" than they used to be thanks to possible experience reimbursement.)

I showed you how to tell his position at the entrance. Whether you follow that advice or not is up to you :) You can save whenever. It's just that your position gets reset to town and monsters respawn. In single player, it even saves the maps.

As for the difficulties, yes. With LoD, Normal has been relegated to a snoozefest. It was a very valid difficulty in regular D2.

The floor in the room he's in has a lot of bodies on the floor, IIRC. You'll find out why. :)

Actually, the whole temple he's in (the entire structure) appears to be built of blood and bone with victims everywhere, particularly in D2R. As for his corpse explosion power, I believe he can only use it on the bodies of his followers who you have killed.

I appreciate everyone helping me out. I am tired of searching for it.