"Fire a beam from your fingertips and mow down the enemy!"
The user charges a finger beam in their left hand, then swipes from right to left, mowing down enemies in its path.
It is apparently a combination of Frieza's Death Beam and the Photon Wave used by her numerical predecessor, Android 20 as it is essentially a Death Beam fired with the same sweeping motion as the original Photon Wave. It should be noted that like Cell, Android 21 has Frieza and King Cold's cells due to having Cell's bio-essence incorporated into her, while Photon Wave technique was invented by Dr. Gero and previously utilized by both Android 19 and 20.
Video Game Appearances
This technique first appeared in Dragon Ball FighterZ under the name Photon Wave.
This technique was named in Dragon Ball Xenoverse 2 as part of the Ultra Pack 2 DLC where it appears as one of Android 21's Super Skills which can be obtained by the Future Warrior in the New Parallel Quest 139: "War and Pieces".
In Dragon Ball Legends, it is also named Photon Wave where it appears as the Special Move Arts for Android #21. While it shares the same name as Android #20's Special Move Arts, Android #21's Photon Wave is based upon her Photon Wave Super Attack from Dragon Ball FighterZ. Additionally Android #21 can also teach it to Shallot (DBL00-01) after reaching Friendship Rank 2.