Here what I though:
CK - what's the point of granting him heal, his illusions are already tanky, do +1 illusion, like a part meepos agha, or even augmente damage bone by illusions.
Sniper should make It pure and passing though bkb, making it AoE will not grant his ult better use, his ult is used as a finisher unless you combo with some wombo combo like zeus you ult before a zeus gank, but then again, no aoe needed.
Centaur - isn't a real bad, but would be better make it's duration longer too, so it can use better for start and fleeing.
Legion - gaining more point per duel isn't bad at all, but considering the status, it's not efficient, a better way, was to count won duel and the make everyone like they where gan at the current level of aghanin's upgaded ult.
Kunkka - I don't think adding a DoT would make sense for a boat hitting you, you have a DoT applied for tetanus? Would make more sense if you add damage amplification or augmente stun duration, or at least goin gthroug bkb, but it's not loree-wise adding a DoT at his ult.
Wraith King - It's not this bad, but you need to remenber that him isn't about illusions, a better usage of aghanins would be remove mana cost from ult, strong yes, but then, for a carry that don't have agha yet to use the new one it needs to be pretty good, CD reduction would't be nice because the let's say it haves if so 130/80/30 s of cd, for a fully farmed with aegis WK this would mean that he istrully immortal.
Bloodseeker - This DoT is too high, what you could do is again putting a dmage amplification at him, and silence the target, same motive of WK, new agha for a "old" carry.
Morphling - I Don't think I really have an idea, but I fell a wast of gold building an ags for this upgrade.
Slark - actually pretty cool, but would be better if it reduced his cd too, cause silence silence wouldn't do much once you can't be revealed while ulted, making the silence nearly useless
Templar Assassin - Since his ult is more used for scouting and map control, would be more useful upgrading his others skills, like more charges for refraction and more armore reduction for meld.