That idea came across my mind some time ago. Not as literal representation, but at least with some reference and architecture. Mac'Aree palace might look much like the city of Dis, for example. Layout can be semi-circular, as we first clear the palace's entrance, chambers and the throne room, and then go deeper down to the otherwise unaccessible plato (reference to the icy lake, you know). This place is actually a giant portal built to give Sargeras access to enter Argus via Twisting Nether at any moment.
Bosses are 4 types: 1) Well-known names, 2) Strongest demons of their kind, 3) Corrupted and mechanical creatures 4) Biblical archetypal demons. 2 and 4 can sometimes overlap.
So, the composition is like that:
1. Palace's entrance. 2-3 bosses. Possible candidates are:
- Magtheridon (but he can be made a world boss, which would be sad indeed)
- A couple of biggest mo'arg brutes.
- Some dog-like beast.
- Giant abyssal and/or felships, cannons, reavers etc.
2. Technical and command wing:
- Nathrezim council (Varimathras possibly included).
- The great soul engine (like Blast Furnace or Thogar, Malchezaar as the operator).
- Aranasi queen (this is basically Ungoliant is compared to the Silmarillion myth).
3. Prison and library wing:
- Corrupted races from Aldrachi or other to constellars or argussian big animals (can be more than 1 boss).
- Possible voidwalker or corrupted Naaru.
- The Grand Inquisitor (this just HAS to be there, I want to more about them. Reperesnts Heresy, demon of forbidden knowledge).
4. Main halls of the Palce wing:
- Hakkar the Houndmaster (blazing skeleton form, Kennel location).
- Astarte the Mistress of succubi (Lust sin. Really want this one cause seduction, temptation and struggle with passion as a boss sound fresh).
- Jaraxxus (or maybe not cause he can be a 5-man boss or world boss).
- Talgath (left in charge by Kil'Jaeden, fought in the Throne room of Kil'Jaeden).
5. The deepest pits of Hell wing (bosses who are either producers of demons, too big or too crazy to be sent throught the portals):
- Tiamath, the Imp matriarch (giant fat lady who generates TONS of imps and felbats, Gluttony sin).
- Baal (of Beelzebub), huge, crazed demon who attacks even his kin, similar to doomlord or Diablo - with 3 faces or more, in chains and fire).
- Belial (Azazel, Abaddon) - a unique spawn of Twisting Nether, greatly deceptive soul-eater who was overpowered and chained at the very bottom by Sargeras himself. Can change his looks into creatures of light, looks like a classical demon, full of souls. Even Archimonde feared him. He possibly created the Jailors.
6. The final wing where we exit the Pit via tunnel and get to the Plato (reference to Armageddon as well) where Sargeras is summoned.
- Sargeras (obvious Satan's archetype).