Anub'Rekhan is a big bug spider-thing that looks like Buru the Gorger from AQ20 except that Blizzard decided to put some time into the artwork this time.  He starts with two guards that can be despawned by exploiting a minor bug (more on this later).

We pulled Anub'Rekhan across the room back to the spot where we started.

The group spread out and started burning him down.  The first attack one runs into is Anub'Rekhan's Impale attack, which I understand is straight out of Warcraft III.  It does a couple thousand damage itself and then shoots you high into the air after which you take falling damage.

Every 90 seconds, Anub'Rekhan casts a spell called "Locust Swarm," which hits everyone within a 40 yard radius with a nasty stacking dot that also silences you.  Basically, you will die if it his you if you don't get a lot of heals or don't have a lot of nature resistance equipment on.  Don't bother wearing NR gear, though.  Just avoid the locust swarm in the first place.

On this first run, when our main tank saw with spell alert that Anub'Rekhan was casting Locust Swarm, he quaffed a speed potion and ran along the edge of the central platform to avoid the swarm himself and keep Anub'Rekhan away from the rest of the raid.  At the same time that Anub'Rekhan casts Locust Swarm, a Crypt Guard spawns that the main raid has to take care of.

At first, whenever I got Impaled, I cast Levitate on myself as I returned to Earth in order to avoid fall damage.  However, I later realized that this was a waste of light feathers.  The fall only causes an additional 500-600 falling damage, which can be healed easily, and there is no need for a priest to take himself or herself out of the fight for a couple extra seconds as one floats down just to avoid the damage.

In addition, a cluster of Corpse Scarabs (five?) will spawn about 10 seconds after a Crypt Guard dies and also immediately after any player dies.  Don't let their small size fool you.  The scarabs can eat up cloth wearers quickly, and if they aren't dealt with, more people will die, more scarabs will spawn, and a raid wipe will follow soon after.

We did pretty well for our first attempt.  We managed one transition across the room and for the most part kept everyone up.  But a few people died here and there and then our main tank got caught by Anub'Rekhan on the second transition, and a raid wipe quickly followed.

After you die, it's easy to find your way back to Naxxramas.  Just follow the ant trail on your map.  The entrance isn't indicated on the map, but it's in a ziggurat in the middle of Plaugewood located at the top end of the ant trail you can see above.

When you port back in after dying, you get greeted by the special vendor Jimmy McWeaksauce who can repair gear (no longer for free!) and will sell you all the major healing and mana potions you want for free.  I wish he'd be kept in for retail!