Scroll of Blight is a Rare Scroll found in Baldur's Gate 3.
It allows you a free cast of the 
Blightspell.
Scrolls can be scribed by a Wizard to learn the spell permanently.
Where to Get the Scroll of Blight in Baldur's Gate 3
The Scroll of Blight can be acquired through purchase from traders or by seizing them from a variety of containers and enemies.