It was choose to add 1 or 2 jinzo to deck and the option came up at start of game but last few games it is showing 21 cards in deck at start and not giving option so I think it was now nerfed to just add 1 to deck.
They need to add an upgrade :
Can be used when your Life Points decrease by 1800. Instead of conducting your normal draw, "Jinzo" is added to your hand from your deck. This Skill can only be used once per Duel.