Trailblazer's Gear
I don’t personally use it but it is currently used in WvW meta.
http://metabattle.com/wiki/Build:Reaper_-_Epidemic
Trailblazers is the go to stat for condition necros in WvW. Basically any roaming condition build can run with trailblazers and do well in WvW. Much like dire it gives the defensive stats some necros need and has increased condi duration which makes a difference in fights.
The build Lahmia linked is largely for zerging/medium group roaming (5-10) and works well with trailblazers.
I currently run viper for my WvW roaming necro, but trailblazer would work well too if you’re less experienced/facing larger outnumber situations. Third utility slot is whatever you want it to be, with epidemic (better in larger fights), spectral armor (better in small groups/1v1s), “Nothing can Save You” (my personal choice/gives you unblockable and boon strip) or even well of corruption.
Violent Tendency [vT]
Ferguson’s Crossing Roamer
Trailblazer has super synergy with viper and you can mix the 2 back and forth for various amounts of offense / defense. It also goes fairly well with sinister and carrion on the cheap end of things.
I tend to run a group build with it and change up on the fly depending on what is needed.
Dire is a fraction of the price. You wouldn’t use either set in pve and there is so much cleanse in wvw that you might as well go dire and do more damage per tick.