The NEW VARIANT; may include a wild card added to the original 52 card deck.
For example, a JOKER.
This Joker, is WILD, simplymeaning, it is any of the 52 cards in the deck, with ONLY ONE EXCEPTION.
That EXCEPTION IS, the original live card in the current playing hand.
The player with the wildcard (Joker) may use it as an Ace of Spade, completing a Royal Flush, in Spades. Which is fine.
However; if any opposing player has that original Ace of Spade, it automatically makes the Joker, and thus, that entire hand, invalid.
Had the Joker been used as the 9 of Spade, A Straight Flush is a valid hand, providing no player in that specific hand, holds that original 9 of Spade.
The Joker, becomes Neutral or Invalid, however, the other remaining original card, remains valid, irrespective of the player with the Joker, calling their Joker a specified card, which an existing player in that same hand, possesses. (By chance).