The mechanics would be that when creating your deck, regardless of what is always done, you can choose a card for each faction (this card can be neutral as well). This card is the Cursed Card,
When you play against an opponent of a faction and include the cursed card in his deck, it becomes a token card (for example an artifact without skills).
With this, if a combo becomes dominant in a faction, people will choose as a cursed card the card that makes it possible. In this way, players will try to make their strong decks without using the powerful unbalanced cards that anyone would choose. Or at least others not so popular and there would be more variety.
When you play against an opponent of a faction and include the cursed card in his deck, it becomes a token card (for example an artifact without skills).
With this, if a combo becomes dominant in a faction, people will choose as a cursed card the card that makes it possible. In this way, players will try to make their strong decks without using the powerful unbalanced cards that anyone would choose. Or at least others not so popular and there would be more variety.