Not sure if someone already mentioned her, but Illaoi? I have nearly 400k on illaoi and she definitely has a lot to work with more than she looks; her passive is something you can utilize much more the more you play her. She is basic at first; you can easily just E-R-W players with one tentacle on a wall and win against people who just run at you. This will only work at lower levels, of course. Her tankiness, healing, and items along with her range makes her rather forgiving as long you don’t over extend, despite the fact she’s very immobile.

But beyond this, her ult can be used to dodge CC, her E and Q are both skillshots that don’t get canceled once they’re cast meaning you can take surprising trades against many champions while also feeling rewarded with hitting them. Her E in particular has a myriad of interactions and is fun to experiment with and use.

She has a decent bit of item variation, but generally Black Cleaver steraks and Deaths dance is core most games.

As for runes, you have a lot to play around with. Klepto is generally best, but conqueror, grasp, and even glacial all work on her well, but in specific situations.