This is the best dungeon I've ever read, and it's free. That's insane. When I first ran this dungeon one player collapsed on the floor and shouted at the ceiling, "THAT WAS AWESOME!!!"

This is the module that made me fall in love with dungeon design. It's full of potent environmental storytelling, insane over-the-top ideas, and comes with terrifying monster designs plus dungeon-specific mechanics to make things special. There's a monster called a "Whirlwind of Living Invisible Dancing Vorpal Khopeshes of Extinction". There's a mechanic for rumors you've heard of the dungeon that let you ferret out the false ones while exploring to give you an edge. There's a real time time limit that keeps players tense and focused. There's also a bunch of great monster stat blocks, which is one thing nearly everyone agrees 4th edition did well - and those monsters can be adapted easily to any ruleset by just taking your favorite bits and cutting the rest.

The one thing I'll call out is that the dungeon is entirely unforgiving, to the point of being unfair at times. This is not a dealbreaker, just read through it before playing (it's one of those modules, you really shouldn't run it live at the table - you'll miss out on some key ideas) and make notes about things you should probably change... Or have people come with disposable characters. Like, there's one thing where if you touch a pillar you instantly die without much warning. That's silly. Just do some brutal damage to the party, afflict them with a temporary curse, or give them a lot more warning. The khopeshes of extinction also have an over-the-top feature where if they kill a living being, they also kill EVERY BEING OF THAT PERSON'S RACE. Kill an elf? No more elves. I changed them to only kill 1 out of 12 of all members of that race on the plane... So we could dramatically roll a d12 for each NPC of the race they know of. See? Now it's perfectly reasonable. ;)

Read this module for ideas, adapt it to your system of choice, and run it for some lucky players. Lean into the grandeur and terror of it, soften the edges a bit to make it feel evil but "fair"... And it's one of the best dang dungeons you'll ever hold in your hands.

Oh, and the stat block it uses for the iron lich? I've used that statblock to inspire most of my future liches. So many evil spells that feel so perfect for a lich.

5/5. For the price? 10/5. It's FREE.

The point I read and ran Revenge of the Iron Lich years ago was the point where I felt I truly had become a great dungeon master, and I could not have done it without this. This adventure is perfectly designed to be fast paced and extremely fun. I especially love the use of "real time" in the adventure, which has significantly helped to keep player attention at the table, and the "rumor system."

And of course, the over the top hyper-deadliness gets the blood pumping like nothing else. One of my favorite adventures ever written, hands down.