Black

Black is a level 99 Legendary Dagger. Although it has a large spell damage bonus alongside its Fire and Thunder base damage, it slowly drains mana over time while used; it is a necessity to continue killing mobs to gain mana back.

Lore
"Hewn from the great obsidian spires surrounding the massive Nether gate, this fiercely-hooked dagger absorbs light and magic energy alike to create a desolate void wherever it is wielded."

Trivia

 * As of the 1.14 Gavel Update, Black (along with Cascade, Tidebinder and Cluster) has replaced Chakram as the highest-levelled non-quest Legendary Dagger.