First of all I’m not an expert.
At a beginner level his speeds are really good and his straights are very high reward. Also the randomness of his abilities can get you out of bad spots. The reason he isn’t a common beginner pick is just because of how easy the Argagarg/DeGrey counterpicks are to play.
At higher levels he is probably the most “personal accountant” in the game and there’s lots of card counting to know the rewards of certain plays. He’s an inevitability character but you have to know how to set up poker flourish and which poker flourish to go for. While the 4 of a kind ace route is the most common, it takes awhile to set up. Of the inevitabilty characters he requires an enormous hand size and its not as straightforward as say “win combat while TD is active”, “land big super”, or have “Joker backup and overdose/chipout”.
For more analysis by a Lum player this guide could be good. It shows what type of mindset you need to play this character. Very math heavy.