The Elden Ring Rolling Sparks Ash of War is one you'll want to pick up if you're planning on using one of the new Perfume Bottle weapons in the Shadow of the Erdtree expansion. It causes a chain of explosions in front of you, giving you a far higher damage output than the weapon alone could manage.
This Ash of War is so powerful that it may well be nerfed in a future patch, since it can take out bosses in a few hits, despite the DLC generally being regarded—and even criticised—as being brutally difficult.