Death Storm is a Skill used by Ranga. It is a Composite Skill made from Black Lightning and Wind Manipulation, with a devastating range. The skill may be fully directed in a way to avoid one's allies. There is also a single-target version of it that focuses all the destructive energies from the storm into a single enhanced Black Lightning bolt.
After having achieved the form he had been told to aim for by his master Rimuru Tempest, Ranga directed his magical energy into his horns and roared, causing many pillars of lightning to appear, connecting the heavens and the earth, as well as a winding waterspout. It was able to vaporize an Orc General in an instant, as well as defeat many surrounding orcs while avoiding damage to allies. Ranga later used the single target version on the Orc Disaster Geld.
In the manga, the number of waterspouts is larger than described, and the absurd range of the technique is more easily contemplated. The pillars of lightning are also replaced by actual lightning strikes, and dense dark clouds form in the area above Ranga.