In Guild Wars 1, we've all pretty much heard about (or fought) the Lich Lord. So I suggest that in Guild Wars 2 you may become a Lich, by collecting a series of items (similar to the "Scavenger Hunt" to get a Black Moa Chick), etc. I suggest that Lichdom would add in special skills, titles, and an increase of health/energy.
Skill Suggestion: 30 15 Call of Blood, For 5...10...15 seconds, each of your skills/attacks against an enemy steal 10-20-40 damage. When this skill ends, you are shadowstepped to target foe and gain +1 energy regeneration for 10 seconds.