Champions you wouldn't expect to be pubstompers, but are.
Things like Katarina, Talon, and Fizz are obvious and expected for this.
But I was shocked at how good Lux support is at stomping low.
Having no real experience on her I get an S and hard carry, just by having experience on other more positonally difficult mid lane mages like Viktor or Ziggs.
You wouldn't at first glance think that an immobile AP caster would br able to carry so hard. But she actually has a combination of things you don't normally find together.
- High burst damage potential. Either single or AoE.
- Strong CC
The key to why shes good is shes not dependant on her team. She can solo kill. She can output enough damage in a teamfight to AP carry. But she can also enable her team with CC to open up opportunities, or to save teammates. You have the flexility to do both. If your team is good, support them. If not, carry them.
I would love to find more champions with this kind of potential.
? Support and mid. She's wonderfully flexible, able to effectively create or absorb pressure as needed, decent at snowballing but easily playable from behind, and functions well in both extended laning phases and in early teamfights/skirmishes.
to be totally honest. Lower elo players never expect the damage output in midlane. I used to play her a lot mid, I remember the countless enemy assassin's get half their hp blasted with one empowered Q. Her build is also flexible in that if you fall behind you can buy 
and stay useful to your team (speaking as if you're in mid lane). Of course you can also sup with her but mid lane is much more fun :))
I have no idea why noone plays this champion, she is f*cking amazing every time I play her. Solid escapes with E, very long stun with W+R combo, free zonya at lvl 6 if you R yourself AND it heals you, her Q is free every now n then thanks to passive. SOLID PICK!
built full ap.
no1 expected the burst/team fight damage.