Mark of Pain
This is an UNTESTED PvE build. This is how it should work: you see a group of enemies. First cast Mark of Pain on the creature that you think will be the toughest to kill. Then, cast parasitic bond on a weak enemy. Keep casting parasitic bond when you have the chance. Spam Barrage, which should be very effective when Mark of Pain’s damage is factored in. If your health starts getting low, use lightning reflexes and start focus firing an enemy that you had cast Parasitic Bond on earlier. If you get in a boss situation, Use lightning reflexes, and spam distracting shot and penetrating attack. Antidote Signet was thrown in for obvious reasons.