Talk to Jiaju Tai in Lion's Arch to travel to D'Alessio Seaboard, where Hakewood is located. Travel north off of the beach and follow the path straight to Dinas, who will open the nearby gate and update your quest. Progress through the swamp. Several groups of White Mantle line the path to the temple, but none are larger than 4 mobs, and most are only 2. They should provide minimal challenge, just focus on killing healers and foes with resurrection skills first. Several groups can be easily bypassed.