Cards that convert resourceshere, creatures into Treasure tokensare staples of combos and other shenanigans possible in the format, so finding a home for Ruthless Knave shouldn't be hard
Use a Pokemons ability (these will usually be once per turn, per Pokmon, but will be specified on the card)
Energy Symbols - compare the energy symbols between the two cards
Lier, Disciple of the Drowned and Past in Flames help give all instants and sorceries in your graveyard flashback, while Creeping Renaissance can return a permanent type of your choice to your hand from the graveyard
However, he finally got his own card in the Modern Horizon set, albeit one that depicts him prior to his ascension to godhood
Elsewhere, a figure of $2 million is widely circulated, but this does not seem to have a verifiable source attached