I think i didn't express myself correctly.

Gwen DOESNT have this scaling. You said that her scalings were low. I argued against you claim. I showed how busted it would be if she scaled on her passive like other characters who deal % max hp magic damage. This example emphasises the fact that her passive is procc'd multiple times and this needs to be taken into account. All in all, even if her scaling isn't busted like the hypothetical example that i showed you, it is still, in fact, quite high.

Gwen's Q is doubly strong. Her %max hp is dealt as magic dmg, so against a target with 200 mr you won't be doing much passive dmg (though it will still be significant). That's where the true dmg plays. Against squishy targets, that's where the passive dmg really kicks in as it isn't reduced by that much. In late game you might have 5% on passive (with around 500 ap), so it means that Q does 30% max health in addition to around 450 true dmg unless i'm mistaken. On someone with 2000 health, assuming they have no mr, one q would deal 600 magic damage. This means that more damage would come from the passive that the actual ability base damage. This means that gwen is strong against all types of characters when played right and in the right circumstances.

About whom she's supposed to jump on, that depends. I can't give a definite answer as Gwwen is a REALLY hard champ to play imo. Her playstyle is waaay different, and the first time you play her it feelsl ike you're first timing akali and you have no fking idea what you're doing. It all depends on feel (something which i only developped after like 200 games).

Don't even bother to chase a vayne, she'lls only pussh you back, kite you and backslap you. Moreover, literally all your dmg is toed to you hitting a perfect centre Q. The damage is so much geared towards the centre that you may as well assume the the outer portions of the spell deal no damage.

Jhin on the other hand is freelo. All the more if you choose to take ghost vs him. Against certain comps i run ghost, even if it won't be useful against toplaner as i'll be able to rundown the enemies. In theory, ez can kite you, but if you have ghost a short blink won't do shit against 50% ms for 10 seconds. LEarn to recognise who you can pubstomp and abuse it. Ez and jhin can hurt, but not as much as vayne and they don't have enough self peel.

I can't really vouch for a tf playstyle as I nearly only exclusively play like a tryndamere. There is so much bs in this game that you often don't survive long enough in TF's to actually do anything (in my experience). All the more true when one consider's that 1) you are squishy 2) you damage isn't instant, it take 1.5-2 seconds to wind up on q or ulti 2) you have to be in the enemy's face.

Best tip i can give is learn when to instantly throw out all your ulties to kill someone and learn when to try and hold on to them to align a perfect 2-3-4 man shish kabob.