Boomerang is spinning a J/L piece into a Super T-Spin Double or similar hole. The strongest aspect of the Boomerang is the ability to fix STSDs ruined by an extra hole below the overhang side of the setup, most likely caused by receiving a line of garbage. In this scenario, spinning in a T will not work as the T would fall one block and only clear a single while leaving a bad playfield afterwards.
Doing this setup shifts the well over one block, so to fix this one may make a TD Attack or Imperial Cross over the resulting field.
