Let's say I have {Witchbane Orb}, giving me hexproof. Could {Slaughter Games} still target me because it can't be countered by spells or abilities?
No. Weirdly enough can not be countered spells can be countered by becoming illegal.
No, it could not target you. This is because {Witchbane Orb} does not counter spells that target you; it just makes it so that they can't even target you in the first place.
Compare that to {Chalice of the Void}, to see the difference.
RESOLVED