So the game is Japanese and the translation is in English, so why the heck do we have a card called Der Freischütz that has abilities called Freikugel?
For starters, these names are German, for those who don't know a good umlaut when they see one. Der Freischütz means "The Marksman." Freikugel is often translated as "Magic Bullet" although I think it's literally "Free Ball" as in musket ball. Our Der Freischütz, however, seems to be just throwing a metal ball, although those pouches around his belt could be gunpowder.
First of all, you may already be wondering where you've heard this reference before. Der Freischütz and the Freikugel or "Magic Bullets" probably sound somewhat familiar. Both names make their appearances in popular culture, especially video games such as Shin Megami Tensei: Nocturne. However, I can't guarantee their all translated properly as Freikugel is in Nocturne.
To find the real origins of the word, we can hit up wikipedia's article on Der Freischütz, which is pretty exhaustive. It's an important German Opera by Weber from the 1800's.
One fun fact is that during the Opera, our hero (who is of course a marksman) is persuaded by his friend, who is a Warlock, to use Freikugel or "Magic Bullets" provided by the Dark Hunter. The Dark Hunter is clearly a devil-figure, and the Magic Bullets are able to unerringly hit and kill any target. Of course doom awaits our hero if he uses the Freikugel, in the form of the Dark Hunter taking him away to hades. Thankfully, a happy ending is possible thanks to the selfless acts of other characters, and instead of our hero being taken away, his best friend (who is a warlock, remember) goes to hades instead.
So let's get this straight, in order to unerringly kill his target, the Der Freischütz lets his friend the warlock die. It's almost as if he set one friendly Lawtia unit to HP=0 in order to set one target enemy unit within range to HP=0. This has to be one of the 10 most accurate adaptions of a 19th century German opera into an online card dueling game skill I've ever seen. And he totally cut out a song out of the last act about "spending 1 SP" during rewrites because too many of his listeners had no idea what that ment.
To add a final bit of coincidence into the mix, as our translator, aka GM Arakis was translating this, he was also working on translating the Manga Hellsing. In Hellsing there is a German character who fights with a giant musket that shoots (you guessed it) Magic Bullets. As she does so, she constantly sings entire versus from Der Freischütz, word for word.
"Scissors are overpowered. Rock is fine." -Paper