Darkwave is a spell that creates a stream of black waves that cause significant damage to the target. Though primarily used by the Blood Spiral, a number of the Organization's Suits have been taught the spell. According to the Suit Handbook, Darkwave is dangerous to use while chasing a target as one's feet would not be firmly planted. LGS-078 This spell is similar to the Bladestorm and Bladewave spells also used by the Blood Spiral.
When Darkwave was used in the underwater city of Atlantis by Rassimov, the spell created a large explosion, scattering the members of Dante Vale's team. S1E21