Rift Quest:The Amber Throne  

Amortsey Swarte can be found outside of Meridian in Freemarch. Wait for him to patrol away from the guards (they are 52 elites) and then attack. Sometimes he will stay and fight, sometimes he will run towards the guards. Be prepared to use slow and roots to insure he stays put long enough for you to whittle through his 3000 health.

Collect the Tome of Amber off of his corpse. This screenshot shows where you can wait for him on a PVE server without being flagged for PVP combat.