Depends on what is going on. I run d/d + sb. I support zergs and keep defenses by setting up poison fields and raining down bleeding damage with my bombs. This is obviously the most boring aspect of thf play.
Most of the time in WvW I’m skirting around behind enemy zergs, taking out the stragglers in the back of the pack, or grabbing a friend and putting myself between a zerg and a respawn point to delay enemy reinforcements.
edit to note: Another priceless aspect of the thf in wvw is shadow refuge rezzing. Traited for stealth duration, it can protect you and a fallen companion long enough to rez even when surrounded.