A special condition that allows you to change the deck/hand of both players. Whenever it activates, the player that initiated it shuffles a card from their hand into the opponent’s deck, and draws another card. They can then choose to swap a card from their hand for a card in the opponent’s.
Scroll Bandit, but with new text such as Backstab: Manipulate
Whenever that Scroll Bandit backstabs, you are brought to a selection screen (similar to like placing walls, targeting stuff with alch, teleports etc, except the hand can be seen at the top (and the replace button becomes a trash can sort of thing). The player can drag a card to the replace button, or press skip, and then they are brought to a second selection screen consisting of the same thing, where they could press skip again, if desired.
For example, you have a hand with 2 Swamp Entanglers, and you decide to shuffle one into the opponent’s deck, and draw a card, and you also decide to give one to your opponent in exchange for another card.
Yes, I realize its overly complicated, and completely fails in a “Lightning Fast Battles” game, and embraces almost 0 tactics.