However Forgeworld also provided experimental rules for this model and it's the first breath of life i've seen come from Chaos in a long time. The rules are good. It's something i'd play!
The model comes in at a modest 155pts but what are you getting for this cost?
What are the other weapon options you ask?
For his special rules he has demonic possession which means he ignores crew shaken and stunned (You take a -1 BS when you take that upgrade so that explains his 3 ballistic skill). Unholy Vigour is where this model gets interesting. Whenever he suffers a weapon destroyed or immobilized results, he ignores it on a 5+ (this is neat by itself, but wait there is more!) additionally, if he is destroyed, place him on his side and for each subsequent player turn on a roll of a 6 he comes back from the dead with all its weapons and mobility restored! This means that once he goes down, he remains a constant threat with the chance to come back from the dead. However on the roll of a 1, he is permanently destroyed.
You can also buy him a mark of chaos but it must match a mark that one of your independent characters have.
The Nurgle mark is particularly interesting. You not only get to reroll the 5+ to ignore a weapon destroyed or immobilized result but also his ability to come back from the dead.
He does have some fairly serious negatives. The most glaring, is his initiative. He'll be spanked if he goes up against a dreadnight or dreadnought. His side armor being an 11 is also fairly alarming. I understand that his BS is reduced by 1 due to the demonic possession but it really drops his competitiveness.
I would equip him with a Butcher Cannon and a Siege Claw. As much fun as the Siege Claws are, I know that if an opponent were to immobilize him with 2 Siege Claws they would ignore him for the rest of the game. If they destroyed him, he could come back as a threat, but being immobilized guarantees he'll be out of the fight for the rest of the game.
I really like this model. It's got unique rules that are just copy/pasted from the Space Marines, you have unique weapons and a great looking model. Chaos have been so stale for so long and with a new codex on the horizon, this gives me a bit of hope that it may actually be fun again!