DM tips

Here's my DM tips

Tell the players when NPC is lying, unless NPC is really good at lying
Show off enemy powers
Try to meditate morning of d&d game
Set obstacles and problems and let players solve them however they want
Don't use dragons until they're really high level
Never re-use a monster, they get boring really really quickly
For persuasion type conversations, only let players roll after when the NPC isn't sure how to respond, or when there's an appropriate break in the conversation where you don't know how the NPC would respond
If something doesn't make sense to the players and "show not tell" isn't working, just tell them what's going on
Try to keep the game in a zone of pleasant challenge, "high level" doesn't have to mean "hard"
For stealth, always roll stealth vs perception
Give one-enemy boss fights ability to re-save against powers affecting them by sacrificing their extra actions, these guys can get locked down really really quickly and it's not as fun
For the hardest encounters, think about the tactics your players rely on, and design encounters to bust those tactics
When you aren't sure how a monster will respond to parley, think about its temperament and desires
It's okay for some monsters to be intractable, that's why they're monsters
Always leave room for mystery, things that can't be easily discovered, or secrets that refer to deeper secrets, things hidden inside other things, that way curiosity will be consistently rewarded and also the world will seem (and actually be) both dense and larger than the players
It's okay for some NPCs to be purely good-hearted and helpful, but use these guys sparingly. They can then be treated as an emotional resource to fuck with and threaten. But also they're nice to have around to introduce levity and comfort
When the players panic, slow down combat
As much as possible, re-narrate exactly what's happening in combat during each player's turn
Close off all escape routes only sparingly, and when you're prepared for a possible TPK
Tumblr is still a good resource for ideas
D&d is most fun when there are vivid and strange characters to talk to, so put opportunities for that in every session

Ok that's all I got for now

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.