Luigi (SSB4)/Down tilt
A back shin kick. It can potentially trip opponents at low percentages, and is able to hit opponents that are trying to grab the edge.
In 1.1.0, it was adjusted substantially. The change to the Sakurai angle made it much less reliable as a combo starter. At the same time, it became more efficient as way to edgeguard, although only slightly. Sooner interruptibility was a direct buff, while a lowered tripping chance was a nerf.
Due to this, down tilt is considered Luigi's worst move because everything it does can be done better by another move.