Gird yourself for spoilers....
The new lair assault goes like this:
Go to wizard's manor. Fight his apprentice, who can teleport around the manor as a free action. In each room, she can activate a different minor action power, like making a painting shoot fire, or having an invisible stalker attack.
Then you go into the wizard's dungeon, where the PCs appear in random rooms and may end up alone against a bunch of giant monsters. And then, if they survive, they come upon the wizard who is showing off his beholder-like construct to his eight apprentices (minions, thankfully).
It is really good.
I have run it twice, once in an "official" capacity at a game store, and then again tonight in a home game. Both times, it was modified. For the home game, it was toned down to not be so difficult. As for the game store, well...
Here is what I have learned about Lair Assaults. The whole idea is to run a super-challenging, deadly mega-encounter for min/maxers and power gamers to try to "win" like it's a video game. But in my experience, those types of players hate to be challenged.
There is nothing worse to them than dying in this game (except rolling a 1 on a d20). And in 4e, dying is an excruciating process of death saves. The player sits at the table for about an hour of real life time doing nothing more than rolling a death save and being sad that it wasn't a 20.
Months back I ran Tyrantclaw the way it was supposed to be run. And it was poorly received. Nobody wanted to try again. They moped at having been "defeated".
Then I ran Spiderkiller, not in nightmare mode, not in regular mode, but in "Wet Dream Mode". As in, I made it easy. They loved it. And same thing happened with Kill the Wizard.
Maybe this is just a local thing. I want to see Lair Assault continue (I want poster maps!), but I wonder if it will see enough player support.