Ho ho ho! I thought it'd never happen!
It's Sombra's Villain Song, featured in Sombra in G Minor.
It's amateur, to be sure. My mic has a distinct background buzz that I can't completely get rid of, the music overpowers my weak singing, and my timing is messed up ever so slightly at the beginning...
But it's mine, by golly! I made a freaking song all by myself!