Vegeta charges ki in both of his hands like a variant of Final Flash and then releases it similar to a Double Galick Cannon, resulting in a devastating beam capable of greatly damaging even those who are stronger than Vegeta himself.
After Vegeta powers up and saves Goku, he uses this attack against Goku Black and Future Zamasu (who had both individually morphed into Fused Zamasu). The attack was strong enough to blow the duo into pieces, however, they regenerate and multiply into more Zamasus. It is noted by Future Trunks that this technique is extremely detrimental to Vegeta and that it was not a good idea for him to use it while already battle damaged. Due to such massive amount of ki released it drains the last of Vegeta's energy and returns to his base form.