Pantheon's Skill Max Order: Q → E → W
Matchup Tip: Your E can cancel Pantheons W in mid air, resulting in you not getting stunned and being pushed to safety. If you anticipate him Wing on you, put your mouse cursor in between you and him and spam your E ability. By doing this, the second he Es your vault will go off because your mouse was in position to E him the second he does it. Only do this if there aren't minions nearby otherwise you will vault a minion. Do this in an open space.
Level 1: Quinn Cheese Level 1 in the bush and then side step his Q after if you can. You hard win level 1. His Q is longer CD than your E now, so you can be as aggro as possible.
Level 2: Level 2 onwards becareful of your E usage. Let him W you, and use your E to cancel his W mid air. Even if your reaction times aren't quick enough, E right after the stun hits you.
Level 3: When you trade with panth and he uses E, do not auto him if you have a harrier on him during his E. This will consume the proc and it won't do damage, so if he Es, wait for the E to expire and then auto him to consume the harrier proc.
Level 6: Be careful of him Ring you if you greed push or if you roam. Otherwise, if he Rs you, be ready to use E to cancel his W because he will use it right away. If you cancel his W with E, you take almost no damage from him.
I really like this matchup after Panth's rework. First, panth was a hard Quinn counter because he had lock on Qs, and his passive meaning that you legit cannot trade with him because he will block your autos.
Now, the rework made the matchup Quinn-favoured (Thanks Rito!!) First, Quinn's E can actually interrupt and cancel Pantheon Q if he is charging it up, but I don't recommend to do this unless his W is down of course lol.
W max harrier procs to side step his spears (which isn't that hard to do since Quinn is so fast under these haste buffs).
Next, the most important interaction to note is that Quinn E CAN cancel Pantheon's W stun, but it's harder to do with new panth.
How it works is if Panth is mid jump, immediately press vault,and if you vault him while he's in mid air, you will cancel the stun and be pushed back to safety.
However, even if you mess this up, it's not that bad because other times, you will still get the vault off even if his stun lands, which is fine because you are still pushed back to safety.
If you anticipate panth using his W and you want to be ready to smurf, (ideally when no minions are near), what you do is hover your mouse cursor in between you and pantheon, and you legit hard spam your E key.
By doing so, since no minions are near, Quinn won't vault anything since you're clicking the ground, BUT, if pantheon uses his W while you are spamming your E between you and him, whenever he uses his W, you will instantly vault him mid air and cancel the jump :) After you vault from his W, you should retaliate with autos.
Panth will likely use his E right after, and that's ok.
Let Panth wear out his E and DON'T auto him when his E is up because not only does he cancel the damage, but also, if a harrier mark is on him when his E is up, you will consume the mark and do no damage, which wastes the mark.
Instead, if your mark is on him while his E is up, just be patient and wait for his E to expire, and since his W is down already, NOW go in for a thiiiicccc trade and you will hard win it.
Quinn hard outscales panth, his only chance is laning phase.
At 2-3 items, you hard DPS him, and with ninja tabis, you mitigate most of his nuke anyway!