Destiny 1 introduced the Black Heart in its vanilla campaign. Much wasn't said other than it needs to be taken out, its a heart of Darkness and the Vex worship it. In Lightfall we search for the Veil and after finding the new exotic LMG in the Black Garden, learn the truth. What the Black Heart was and why it was created.

“Destiny 2 Lightfall"
“Destiny 2 Black Heart"
“Destiny What Is The Black Heart"
“Destiny The Black Heart"

Thanks for watching!