Shuffling cards into your opponent's Deck

[Grumozard]

https://www.duelingbook.com/replay?id=379356-52556467

I bumped into this player who made customs which work like parasyte. Taken by the inspiration i tried to make something with the same gimmick, but even by copypasting the text i cannot have the feature to shuffle into oppo's deck :/

Any hints?

[Christen57]

If you're copying his entire effect word for word on your own card and still not getting the option to put the card in the opposing deck, then he must've used a javascript command / extension or something to enable that option for him to add his own cards to opposing decks.

[Grumozard]

Solved! Indeed wad necessary extention's help