Assassination
A Stalker does his best work when attacking from ambush.
Whenever attacking a target that has his Dodge reduced to his Agility or less, a Stalker does ten extra points of damage.
Build
Much like a scrapper, a scrapper uses Powers skill and Super schticks or Martial Arts skill and Fu schticks, but focuses as much on stealth as on combat.
If going with Powers the obvious power choices are Blast (Melee), Blur Form, and Abysmal Spines.
With Martial Arts, you need either the Intrusion skill or the Catsuit pulp schtick. You will find the Path of the Empty Mind and the Path of the Shadow's Companion highly useful.