Urien Rakarth is the Master Haemonculus. He is said to be several thousand years old, and died just as many times to everything imaginable. So much that he considers death to be like a fine wine, and revels in the pain and knowledge that comes from each one.
His new incarnation in 5th edition brings us a masterpiece of a model. It is quite an amazing piece of work. It is one of those models that whether or not you want to use Urien Rakarth, you should definitely get this model.
His stats are WS5 BS5 S3 T5 W3 I5 A3 Ld9 Sv5+. His toughness 5 is pretty unique amongst our HQs and with feel no pain, he will be one tough model to kill. He comes with Night Vision, Power from Pain, Independent Character, Meld the Flesh, Master Haemonculus, and Father of Pain special rules.
Meld the Flesh means that Rakarth heals a single wound at the beginning of each of his turns. He will be hard to kill. Yes I know there are lots of ways to kill him still, but with 3 wounds, and getting one back each round, he will be tough to knock out.
Master Haemonculus. Urien is a haemonculi, and as such wracks are considered to be troops. In addition any unit of Grotesques can be upgraded to S6 at the cost of +5pts per model. At least they are no longer called "uber grotesques".
Father of Pain. He comes with a pain token, and beyond that he generates D3 more tokens to be placed on either wracks or grotesque units. Each unit can only gain one additional token.
Urien Rakarth is pretty loaded on wargear. He has a close combat weapon, gnarlskin, Casket of Flensing, a clone field, and an Ichor Gauntlet.
The Ichor Gauntlet is a flesh gauntlet that always wounds on a 3+. It causes instant death.
Clone Field. You thought he was tough with feel no pain, toughness 5, and Meld the Flesh? Roll a D3 each round of close combat. That is how many wounds he may completely nullify. Just before rolling to wound, you choose which attacks to nullify.
Casket of Flensing. Once per game shoot 12" Sd6 APd6 Assault 2d6 shots.
Personally I wish he still came with the liquefier he had in 3rd. However I'm sure we can live with the casket. He is meant to be in close combat dealing death rather than shooting.
Urien is a monster on the field. He comes with I5, will be at I6 with a second token. Put with a couple big guys (grotesques), and I'm not sure you will lose him that often. No other dark eldar character will be able to stay alive as long as he can. The combination of regening wounds, T5, Feel no Pain, and the clone shield, should really frustrate your opponent. I'm frustrated just thinking about it.
If you are fielding a mostly Haemonculi/wrack list, Urien Rakarth is your guy. He will work in other types of lists, but they just don't fully take advantage of his bonus's unless going heavy into a Haemonculi Army. To fully take advantage of his abilities combine him up with 3 haemonculi in the other HQ slot. Throw in a couple parasite engines, a talos, some grotesques, and lots of wracks, and you will quickly have an army with feel no pain, furious charge and be completely fearless. Next throw in some heavy shooting to kill armour (we know dark eldar can do this) and Bam, you have a list ready to go.
One of the issues with this army type currently is no models for so much of it. It makes it very hard to create at the moment. Playtesting it is also a "pain in the butt", this is apparently a special GW rule when we don't have models. Sorry for the dry humor. It is very difficult to test as you spend half the game explaining to the opponent what this is, and what that is.
He does come in handy, when you are stealing pain tokens for your archon. It is nice not to have to steal the only token off your wracks as you charge your archon forward. However this alone is not the best use for him
Regardless, I do love the model for Urien Rakarth. While I he will do well in many army types, he excels in the haemonculi lists. He is rather expensive to just throw into most lists, so you really have to construct the army knowing he is there. He should not be your token Haemonculi in order to get wracks as troops. He does help when it comes to sharing the pain. Overall he gets mixed reviews from me. Down the road, some people will love him, and some will simply ignore him. Definitely not a second rate HQ choice, just one for connoisseurs.