so it's settled that he's ALL protoss? i don't like the idea of a manga-based terran hero or anything like that. I was envisioning a new unit altogether. like how spectres were added into campaign and to the editor. what i mean is something you can buy 50 of if you wanted to.
as for the ability to replace emp, how about a force-based psionic crush? something that scrambles all units in a large area into a real small area, and paralyzes em with minor damage. i was thinking that + high templars would be an awesome strategy (since shockwave would hit all the guys cornered in by the crush)
EDIT: this overpowering ability should be balanced out with a required research, or a high energy cost. another ability could be a mutli snipe that hits up to 5 targets with a snipe power that does about a third of the damage of a normal snipe, but cant be used quite as often
lastly, the basic weapon should be a rifle of some sort... not a pistol.
SECOND EDIT: HOLY SHIT I GOT IT!!!! what if the sniper rifle fired a homing projectile?