Thats nothing new... Urgot, Renekton, and Jarvan all reduce their targets armor by a %
All their debuffs are Aoe, Renektons is a stronger debuff at lvl 5 slice and dice (and longer duration), Urgots can be applied from a distance (and longer duration) and synergizes with his kit extremely well, Jarvans can knock people up.
Monkey kings armor reductions the best at level 1 of the skill, but is single target, requires you to be on top of them, but resets your auto attack timer. So to reiterate... nothin really new.
All the other % armor reductions give some feeling of uniqueness, Urgots allows his missiles to become homing, Renektons gives him mobility, and Jarvans gives him reliable CC and a gap closer. Wukongs just seems to be thrown in there with his other abilities, granted it does synergize with his kit (specially ult, though it wears off before your ult does). I personally think the only change he really needs is for decoy to also be a short range dash (think range of a nidalee pounce) as the stealth is entirely too easy to cancel. Its bad design when 2 of a champions abilities are canceled so easily that someone batting their eyelashes at you disrupts and counters half of your skill set.