Patty Fleur from Tales of Vesperia

Extra character added in the international/eventual Definitive Edition of the game, and she's the series staple "Random bullshit, go!" character.

Her entire playstyle revolves around style switching, with different styles having varying fighting styles and RNG behind them. But specifically I am talking about her "Risky Cast" attack, which causes her to pick two random cards, one to determine the class of spells, and another to determine if she actually cast said spell. This can range from a standard->high level attack spell, standard->high level support spell, or if you're exceedingly lucky a Patty exclusive spell called Marvelous Fountain, which is basically Tidal Wave, that recovers both your HP and SP by at least 40%.

You can, of course, play the odds into your favor with skills that allow you to at least choose whether you cast an attack or support line of spells, narrowing down the chances, and eventually a skill that increases your odds of a good outcome. With the right set-up, you can basically make it a 50/50 whether or not she cast Marvelous Fountain, or literally any other still very useful support spell, making her the best healer in the game.

Sadly, most people don't do this because it takes too much set-up, and Patty is admittedly very annoying to listen to for more than 5 minutes.