Rogue they vanish when they take too much damage and take pride in killing when the enemy is most vulnerable.
To this day, the only class that seems to jump me for a gank, when I'm at 20% health and covered in mobs, and dances or laughs after. Course, in a fair fight, double vanish, dodge, then run for their lives.
I think Rogue is the jump to option, but I would say feral druid more than anything. They can just kite you with bleeds ticking and if they're going to die they either go bear or run away with close to 100% success.