It features Drednaw, a tough Water-type turtle Pokmon, as the main attacker, supported by other Water-type Pokmon like Samurott and Barraskewda
For most formats, there's not much public information available on the individuals who make these decisions, but we do know that MTG's Play Design team has some say in what cards are banned
The expansion of Red's slice of the color pie to include playing cards from exile (see Light Up the Stage) has been an absolute boon for the design space, and now Prosper gives you play-from-exile tribal
For just two mana, you get out of committing to a single effect, and now have as many as you have in your graveyard
Needless to say I got my money back minus shipping because Im a sucker and felt bad for him (genuinely believe he got ripped off as a kid) plus he was willing to get the other cards checked my an LCS to confirm my suspicions for everything else I suspected were fake