@Phreak about MF scalings
Since you wrote on reddit and i ain't got a reddit account to answer there and this is Riot Games boards anyways so i find it more obvious to answer here
I never understood this one. R applies and damages Impure Shots. The R has always had an AD ratio. If someone stands in the whole thing, the AD ratio is between 2.16 and 3.84 (compared to 1.6 AP ratio), and then allows you to attack with a 0.48 bonus AD ratio on every auto-attack on targets inside since.
When people say "AD ratios", they mean that those AD ratios on W and R are next to impossible to use due to the damage being magical.
Before the rework it was both AD ratio and Physical damage, so you would benefit from both the stats while now it's just magical (R has got a base physical damage but it's piss low and doesn't scale).
You can obviously go R and then autoattack, but it is not fun, it is not fun to use your main damage spell just to barely do any damage (due to tanks having pretty high HP and mres).
So to clarify the problem with MF: AD ratios are there, but the damage is not physical.
Corki has got magic damage on every spell except E, but Corki has got a no-cooldown ultimate that he can spam endlessly, procs sheen/triforce, has got a silly high range that does let him poke from super safe positions and doesn't root him in place for 2 seconds.
It's not even the fact that she roots herself to use that, it's the fact that she roots herself to put stacks on everyone and THEN she can start to do some damage by AUTOATTACKING from 550 range.
She should deal ALOT of damage with the ult alone just due to the risk of using that, screw the stacks mechanic, she's no Vayne anyways.