From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
First, Ascended Super Saiyan Future Trunks raises his hands and charges a large, golden-yellow energy sphere. He then swings his hands down and fires the attack at his opponent, inflicting a huge amount of damage.
Dragon Ball Z
Ascended Super Saiyan Future Trunks used this attack in an energy wave version against his father, Vegeta. Determined to save the main timeline from Semi-Perfect Cell, Ascended Super Saiyan Future Trunks decided to attack Vegeta and prepared his Finisshu Basutā. While Vegeta initially believed that Ascended Super Saiyan Future Trunks would not attack his own father, he was soon proven wrong as Ascended Super Saiyan Future Trunks attacked Vegeta with the Finisshu Basutā, blasting the surprised Saiyan prince away up into the air and into the ocean.
The Finisshu Basutā appeared in Dragon Ball Z: Sūpā Butōden 2.
It later appeared in the Budokai video game series and the Budokai Tenkaichi video game series and is Future Trunks' and Trunks' Ultimate Blast in their base form (in the Budokai Tenkaichi video game series, instead of a continuous beam as seen in the anime, Trunks only throws a ball of energy at his opponent) and one of Future Trunks' Blast 2 attacks in his Ultra Super Saiyan form.