Long time no see, fellas!
Quinn, if the Korean wiki's information is accurate, is supposedly a rushed champion whose kit doesn't fit any of the end concept. Thus I believe it's only right that someone spoke up and offered his/her idea about adjusting Quinn's kit to first make Quinn much more attractive choice, as well as to address the segregation between character concept and actual moveset.
Now, why Quinn? Because Quinn is IMO one of the very few female non-yordle/child champions who actually have largely reasonable amount of clothing (damnation to all the sex-appeal-loaded champs), besides others like Kayle and Diana, with Lux as an honorable mention. And no, Jinx doesn't count because despite having the glorious flat chest, having nearly no clothing that would do little to prevent even a small debris from hitting delicate parts is a joke. For that matter, Karma goes alongside Jinx: while Karma has more coverage than most, the attire still reveals the sides of the thighs, which leaves a bitter taste in my mouth. Basically speaking, IronStylus is boss
despite siding with the puny resistance for coming up with the Quinn idea, but Quinn unfortunately was given the short end of the stick.
Statwise, only a minor adjustment is given: as a tip to the anti-assassin concept, this probably poor attempt at a Quinn readjust involves small increase in durability, mobility, and quick exchange power by gaining largely nominal increase in HP (390 (+85) to 395 (+88)), damage (48 (+3) to 50 (+3.2)), armor (13.5 (+3.5) to 14 (+3.75)) and speed (335 to 340) in exchange for lower attack speed (.668% (+3.1%) to .625 (+2.8%)).
In terms of holistic design, my idea for Quinn veers towards a support-marksman role, by giving Quinn active abilities to help reduce enemy damage output in general, especially burst damage. Fundamentally, this kit aims to preserve and expand on Quinn's flexibility, although it comes at a cost of steroids and thus reducing Quinn's potential DPS.
The passive and abilities' interaction with Valor is the heart of the tag team concept that is to be given. In retrospect, this passive seems like Orianna's ball and indeed, some of the interactions available will mirror that of Orianna. However, there are subtle differences which are more closely covered in abilities that involve the usage of Valor. In this remake concept, Valor is given a clear role of a supporter, providing utility which includes sight.
The Harrier passive is retained but changed. However, Harrier's passive mark is now controllable, as the mark placing is done by landing an ability on a champion, giving Quinn more control on damage dealing.
I am personally a big fan of the Rumble Ult/Viktor Death Ray's firing mechanism, and the targeting mechanism there is the basis for Airborne Surprise's targeting mechanism.
Swift Strike is quite like Command: Attack in that it orders Valor to move to a position. Whereas Valor can move freely when on the ground, Swift Strike allows Valor to move faster, which is particularly useful in conjunction with Parthian Acrobatics if looking for an escape, or perhaps use him to take an otherwise fatal shot of Javelin Toss. Although its damage output is low, it's still better than Valor's single autoattack.
The ability is a reinvention of the Vault ability, based partially on the Parthian horse archers to whom the term parting shot has originated from. The Parthian shot portion of Quinn's ability is a pass-through linear skillshot similar to Piercing Arrow.
The Angle of Tolerance is a threshold value for the angle between the line segment formed by center point of the enemy first hit by Quinn leaping and center point of Quinn with Quinn's leaping trajectory at the time frame of collision. If the angle is greater than the Angle of Tolerance, Quinn's rebound will go towards the direction pointed by the ray from the center point of the enemy to Quinn instead of the opposite of Quinn's original trajectory.
In overall, Parthian Acrobatics gives Quinn a degree of mobility to expand on Quinn's flexibility. It is not a superskill: for starters, It is not a strong poke as the effective range of Parthian shot is around 675 from the initial point. In addition, the initial range of the leap is very short at 400, far shorter than most skills, making it a poor skill for initiating small-scale fights in the laning phase. Nonetheless, it gives Quinn a far more reliable escape mechanism than the old skill while staying true to Quinn's concept as a mobile striker.