I have now looked over the official builds and found then inadequate in terms of survivability and playstyle. This is simply better for me, BUT do look into getting your boon strips into play when zerging - Greatsword#4, "Nothing Can Save You", Well of Corruption.
FULL DIRE Armour, DIRE trinkets and weapons: This provides high Condition Damage with T & V
RUNE: Undead = Toughness and 7% of Toughness as Condition Damage, synergises with itself.
SR: 321 (Some prefer 221, this is also fine, I use 3 because it means more and better Shroud-play)
Reaper 222 (I change this to 322 when I'm struggling with enemy CC)
For skills I mix it up a fair amount, but generally bear in mind that I want chills and blinds and usually a stun break.
HEAL: Consume conditions, despite huge cast time
Skills: Well of Corruption, You Are All Weaklings (stunbreak), Suffer. Mix this up if you like, but remember that with this build;
anything that does blind also does chill and,
anything that does fear also does chill and,
anything that does chill also does bleed.
Elite: Chilled to the Bone
Food & Utility: Any condi food/Saffron Bread & a bog standard 6%,4% tuning crystal for over 150 more condition damage.
TIP: Fire off Chilled to the Bone, then Suffer and pile up lots of Chill quickly and by extension Bleeds.
TIP: I made this build with the avoidance of having to target enemies in mind. I get jumped by a lot of thieves, so I wanted to be able to use marks and shouts, which don't require target.
TIP: Remember with this build that Fear, Chill and Blind all inflict Bleed.
Zerg Playstyle: Use staff #2 to tickle enemies when sizing up a fight. On enemy push drop Well of Corruption on their tank train, dodge through them and do Chilled to the Bone and Suffer on the backline to reduce their damage output and mobility. Switch to reaper and do #4. Look for enemy tank train and avoid it's return, get back to tag. Consider dropping shroud at this point, depending how much life force you have left.
#2. Remember that when 2 ends it does blind > chill > bleed on 5 targets. In addition, it converts 2 boons to conditions - Fury becomes blind, stab->fear, vigor->bleed, resistance->chilled, etc.
#3 gives you stability and then hit it again to fear > chill > bleed another five nearby.
The #5 is good but takes a long time to cast.
At some point you might be out of shroud, pile up conditions on nearby enemies with chill shouts and get the heck out of there (save that stun break until you need it - it's not part of your chill > bleed routine anyway)! If you find you don't need so much stun breaking, drop Weaklings for Nothing Can Save You.
When Jumped by a Thief: Drop Marks on yourself, when you know thief is near blow it up with shouts. This gets most thieves into a defensive situation, so either press them with Shroud attacks or run away. Sometimes it works. Good luck!
All of this and nearly 30,000 HPs. What more can one ask?
The cheap way to get Dire gear from trading post: https://wiki.guildwars2.com/wiki/Jatoro's_armor