"Nice But Deadly" is an Indie/Electro remix of "MEGALOVANIA" from Undertale's OST. It was going the during the battle with Kitty Rose on Neutral and Pacifist Routes, before the fight was scrapped. The song ended up becoming unused afterwards, as "Kittylovania v1" became the theme for the Genocide Route battle.
A remastered version of the track that was a mashup of "MEGALOVANIA" and "Dummy!" from Undertale was released on YouTube June 21, 2016, but has since been removed alongside any videos relating to Kitty's now scrapped Neutral/Pacifist battle, and hasn't been recovered.