Jack is the Turbo Duel Champion and one of the Legendary Signers bearing the Wings Mark of the Dragon with his signer dragon/ace card being the Red Dragon Archfiend. He is one of Yusei's oldest and closest friends and would help him in his battles throughout the series.
How to Unlock
How to get
Assault Exchange Shuffle 1 "/Assault Mode" card from your hand into the Deck. Add 1 "Assault Mode Activate" from your deck to your hand, This skill can be used once per turn.
Majestic Light Shuffle 1 Tuner monster from your hand into your deck to summon Majestic Dragon from your deck. This skill can be used once per turn.
3 of those skills would involve already having RDA in your extra deck, so hopefully a box comes out soon after Jack, that has Red Dragon Archfiend, plus Dark Resonator. Wouldn’t be surprised if DR wasn’t released though.
Before this I was expecting we will get Black rose box around this time, but instead we get Junk Destroyer.
I was so sure that we would get RDA box during jack's release (24 Jan). But now, I'm not so sure anymore. Next in line is mini box, and RDA in mini box doesn't seem quite fit IMO.:P (not that I'm complaining)
I think they said that it was some copyright issue or something. Something about them not wanting it spread too far over the internet or some other dumb excuse like that that doesn't make sense. I can't remember, I would have to try to find the steam forum where they talked about it. Either way, it sucks. I can't play this on my phone and the trick to get the JP voices does not work for me.