General Malagon of the Cruelest Eye

General Malagon of the Cruelest Eye, one of the four living generals of the slain wizard Illith Varn. He has one horn, his hands are bent like claws, he lives on the second level of the Shattered Labyrinths of Illith Varn in a well-protected sanctum. He has seven wives, all of them are part demon and one of them is half-demon. He's befriended the Deadboyz, the rival adventuring party in the dungeon. He's captured several of the party's attendant louts, as well as Bashro, the four-year-old son of their traveling knight, Vlawyn the Ket. And he guards the way down to level three, which they need to make progress. And on top of all that, he's a powerful wizard, apparently specialized particularly in the spell Disintegrate.

Here are Malagon's known defenses and allies:

An ENCHANTED ANTECHAMBER that traps you in an infinite repetition of mirrored antechambers unless you pass through them in the correct order
ENCHANTED SNAKE-HEAD DOOR-HANDLES, which guard his inner sanctum, and which bite your hand if you don't have the key
A number of THREE-LEGGED CRANE-MEN, all proficient in the fighting arts and able to come back to life
THIRTY HEADLESS FLOATING TORSOS wielding serrated weapons, whom the inhabitants of Malagon's headquarters refer to collectively as NERWO, and suggest may be partially omniscient
HOYVEN LARTH, an adventurer proficient in the rapier, who has abandoned his quest to find his mother's soul, and prefers to spend his day rereading the same crime novel
VARGA and NORN, twin goth sorceresses, wearing ankhs around their necks, and eating black cake. They are bored and wish they could kill something. Their bored cat Bat has told the party they are reluctant to be separated from their ankhs...
The lava elemental TANTRUM, a newt-man who lives in a giant walking metal brazier filled with lava. The brazier's named is CHARD. Tantrum is working for payment in rubies, he would rather live in the Plane of Fire but Malagon is paying him too well.
SIX LOVELY WIVES, each with a different demonic bodypart. Their powers are unknown, but they delight in the soft, perfumed, and lovely things. They have possession of the young boy Bashro.
FELRA, the head of Malagon's harem. Her left half is a bright red scaled demon. She seems to know magic, but powers are unknown.
A DISGUSTING INSECTILE MONSTER, which guards the party's louts. Its powers are unknown.
THE DEADBOYZ, a party of three powerful evil adventurers and their large number (30+) of monstrous Deadboys. Their exact relation to Malagon is unknown, their powers are unknown, and their location is unknown.

Notably, he has captive the SKY WITCH, QUEEN JUPITER VOLARIS, who surely hates him. At this point though, the party has calculated that the Sky Witch probably hates them too, and so they're reluctant to free her.

He sent the party to the Flying Fortress of the Sky Witch in order to recover the Sky Witch's diary, which he has offered in exchange for the boy Bashro. Malagon desires to kill a god, in order to use its blood to forge a Ring of Flight (my players: "so he can... fly around..?"), and in his psychic barrage of the captive Sky Witch's mind was able to determine that she held a useful secret in her fortress, but could not tell what. The party has discovered that the eye of the Sky Witch's adopted daughter, the maiden Xoanna Julius, leads directly into the Celestial Realm of the Witch Goddess Izorides, and so they are reluctant to give Malagon the diary unaltered. Not because they care about the god, but because they like Xoanna, who they have secreted away in a distant and well-guarded black-market auction house, along with her lover, the Prince Aldarys of the Kingdom of Loiveth.

I hope they all fight each other in a huge multi-session brawl but you can't always get what you want.