There is a Vandal in the Forgotten Shore who is as tough as a box of nails encased in iron dipped in treacle, he is level 8! I remember running into him as a level 8 during alpha/beta and he was a very tough but an ultimately satisfying fight (took three of us), now at level 28 I decided to pay him a visit. The odd thing is he appears to be just as strong and is able to take a considerable amount of damage. In comparison I visited the Hallowed Knights in the dark tunnels under the Cosmodrome, they are level 18 (yellow too) and are considerably easier to kill, taking a fraction of the time to dispatch 3 of them compared to the single Vandal. Doesn't make sense to me!