If a player announces activating Vi's ability ("Recycle 10, Vi is 13") but doesn't actually recycle the cards, then Vi enters two combats, can the game be rewound to correct the payment and give Vi the +10 buff?

Ruling: The situation can be rewound back to the first activation of Vi with a warning for mispayment of cost, allowing the player to properly pay the recycle cost. Units that died on the first battlefield are returned, Vi goes back to base, and play continues from there.

Sequence:

• Rewind to the point of Vi's ability activation
• Return units that died on battlefield 1 to the board
• Return Vi to base
• Issue warning to active player for mispayment of cost
• Active player properly pays recycle cost
• Continue play from that point

Nuances:

• Whether the opponent heard the intent to activate Vi matters - if they heard it and said nothing until the second combat, that could be angle-shooting
• Preservation of board state is both players' responsibility
• The rewind is straightforward because no other cards were played and interactions were simple
• Vi's ability is an activated ability, not a triggered ability, so missed trigger rules don't apply
• The term "mispayment" technically only relates to energy and power costs in the rules, though the situation was treated similarly
• If the opponent had reacted, the play could have created ambiguity about whether the ability was actually activated