Reaper's Mark on Bow bar is used for solo AvA; swap Reaper's Mark out for Relentless Focus in group AvA.

Buff yourself up with Rally and Shuffle, then debuff enemy with Reaper's Mark (solo AvA only). Use Ambush and then Surprise Attack for large opening damage. Swap to Bow and cast Poison Injection (keep this DoT up from now on) and then cast Shadowy Disguise. Swap to 2H bar and use Surprise Attack for guaranteed critical strike from Shadowy Disguise and the stun that Surprise Attack grants from stealth.

At this point enemy player has most likely broken out of stun and is fighting back. Swap to Bow bar and cast Resolving Vigor, and keep it up on yourself. Keep the distance closed between yourself and the enemy with Ambush. Keep Rally active on yourself for the heal and damage boost, Shuffle on yourself to avoid attacks, and especially Resolving Vigor active at all times for the self heal. Keep Reaper's Mark and Poison Injection active on enemy player. Weave partial charged heavy attacks and Surprise Attack together for your fillers.

When your HP drops low, cast Shadowy Disguise and heal up using Rally and especially Resolving Vigor. Continue to use the invisibility from Shadowy Disguise to heal up to full whenever you drop to low HP. Use fear when you're on the defensive, and the stun from Surprise Attack when you're on the offensive.

ONCE THE ENEMY PLAYER drops below 40%, use nothing but fear exclusively for CC and stop using Surprise Attack as a filler, instead using Executioner. At this point it is IMPERITIVE that you keep Poison Injection active on the enemy player. Change nothing else in your rotation, remembering to keep Rally and Shuffle active on yourself, and Reaper's Mark active on the enemy.