This is my first guide. I am Quinn main and i want to make a guide featuring her in order to share my experiences made with her.

Pros - Hypercarry potential - High burst/sustained damage - Safe laning due to her W - High mobility - good roaming ability

Cons - Short AA range - Very squishy - no crowd-control - low aoe/multi target damage

Harrier(P)
Valor periodically marks a nearby enemy with Vulnerability for 4 seconds. If Quinn attacks a vulnerable enemy, she deals bonus physical damage equal to 15-105 (+1.16-1.5 per attack damage) depending on her level. This also activates on enemies hit directly by Blinding Assault and Vault.

Harrier is disabled while Behind Enemy Lines is active and for 8 seconds after a target's mark ends, though this cooldown is reduced by 1% per 1% critical strike chance, multiplicatively (ex. at 50% Critical Strike Chance, Harrier's cooldown is ~5 seconds, at 100% Critical Strike Chance, the cooldown is ~3 seconds)

Use your passive to poke enemies. Just poke then.

Blinding Assault(Q)
Quinn commands Valor to fly forwards in a line, stopping when he collides with an enemy and marking it as Vulnerable. In addition, Valor deals 20 / 45 / 70 / 95 / 120 (+0.8 / 0.9 / 1.0 / 1.1 / 1.2 per attack damage) (+50% of ability power) physical damage and applies Nearsight to the target for 2 seconds, removing allied vision and reducing its vision radius to 300 for the duration.

Use your Q as finisher when they try to get away, or use it when you engage to counter enemy attacks.

Heightened Senses(W)
Passive: Attacking a Vulnerable target will increase Quinn's movement speed and attack speed by 20 / 25 / 30 / 35 / 40% for 2 seconds.

Active: Valor reveals the surrounding area for 2 seconds.

Use your W to get vision on bushes if you think someones is hiding. Also use it to prevent ganks or get vision over the jungle.

Vault(E)
Quinn dashes to an enemy, dealing 40 / 70 / 100 / 130 / 160 (+ 20% bonus AD) physical damage and slowing the target's movement speed by 50%. This slow decays over 2 seconds. Upon reaching the target, she leaps off and lands near her maximum attack range away from the target. Valor will immediately mark this target as Vulnerable.

Tag Team: Valor dashes to an enemy, dealing 40 / 70 / 100 / 130 / 160 (+ 20% bonus AD) physical damage and slowing the target's movement speed by 70%. This slow decays over 2 seconds.

Use Vault as engage or get range from meele champions.

Behind Enemy Lines(R)
After channeling for 2 seconds, Quinn calls upon Valor to assist her. While together, the two gain bonus movement speed equal to 70 / 100 / 130% of their total movement speed and can cast Skystrike by taking an offensive action or reactivating Tag Team.

If Quinn takes damage while channeling, Tag Team's cooldown is set to 3 seconds. Basic attacking, dealing direct damage, or taking champion or turret damage causes Quinn to swap in. All other sources of damage disable Tag Team's speed bonuses and slow Quinn and Valor temporarily.

Use your ult to get around the map, it's best for roaming. Also use it to escape.