Katarina's Kit (assassin???)

Ok so when most people see katarina they seem to call her an assassin. in the team builder it even recommends her role as an assassin but when i think of assassins in the game they are champions who can 100 to 0 you in a few seconds flat if u are caught out. katarina can not do this at all. but obviously she is not ment to her passive would make her ridiculous if her damage allowed for a 100 to 0 (and yes i know a reeeeaaaalllly far ahead katarina can do this) however riot you always speak to champion diversity. i know changes are in order for katarina soon (or maybe not anymore) since the removal of DFG. katarina is what i would call an executioner she is meant to wait till the enemy team is low jump in and get a quick penta for the win when they are all low and she is guaranteed her resets. to me this is what DFG should actualy be used for not to make assassination possible on katarina but so that when that one champ is walking away with 2 HP and you dont have resets u can nuke then real quick and continue on your rampage. i think that katarina's ultimate does not fit her kit as an executioner to me it seems like she should have an ultiamte that does damage based on missing heath. similar to garens ult so that u can kill the pesky champs running away. i would also love to see more of a focus in the way her damage is done to killing low health champs instead of standard burst damage.

but dont stop there riot make a new "class" change the game add other champions like katarina in playstyle just like assassins they will be weak early but instead of a champ that can blow up 1 target its a champ that is almost useless untill half of the teamfight is over and they jump in for the penta. (though i might make it more skill oriented add some skillshots or something)

so that is my idea riot pls consider it you always say champion diversity is important pls prove it.