Basically my understanding is:
First part is whenever you "select" a card (use a tarot card that picks card(s) to modify, MAYBE when you play a hand though not sure, discarding) , there is a 1 in 4 chance to proc this joker adding some random effect to the card such as bonus chips, mult, steel, etc.
The second part is whenever you beat a blind, there is a 1 in 10 chance to give one of your other jokers (at random) the Negative buff (+1 joker slots).
Third part is that this joker copies effects of all other jokers you have (blueprint joker but on steroids).
Fourth component is that every HAND you play has a 1 in 50 chance to destroy this joker without financial compensation nor trauma counseling for the fact that you just lost 70 dollars worth of assets on a 2% low-roll.
As for the odds of it showing up, it starts at 1% and every reroll you do increases the odds starting at just under a 1% odds increase. The odds increases from rerolls persist across rounds, and have slightly diminishing returns (i.e. first reroll of the game increases odds slightly more than second, second slightly more than third, etc.).