If it was a creature card, put a +1/+1 counter on this creature and you gain 1 life
TAHK0 speculated on why the error may have happened, writing, Poke Balls went through a lot of early variations, with everything from the button placement changing, to how it opens differing, to even being depicted with the white on top. It could be that an early Pok Ball design actually did open like it does on the card back, but when the design was eventually changed to the opposite way, they forgot to update it on the card back before going to print, and it remains that way to this day
Play that permanent below your seven stacks
Until end of turn, those creatures can't become tapped unless they're being declared as attackers
The only reason Zulaport Cutthroat beat out Blood Artist is that it is a 1/1 rather than a 0/1, and has three creature types that can all work well in black Commander decks, over Blood Artist's lone Vampire typing
Still, understand that each Set pack will give you at least one (and as many as four) rares and/or mythics