Tournament rule 702.8.b.1

If a cost is overpaid and it is still the turn where the cost was paid, the overpaying player is considered to have the extra resources floating in their resource pool.

• 702.8.b.1.a If overpaying a cost was advantageous to the erroring player, this penalty is a [Warning] instead.
• 702.8.b.1.b If overpaying a cost caused a result that would not otherwise have happened, it is a General Error. See 702.15 for…

Official Tournament Rules