When Mandy took control of it before Billy's dad pulled down the pants to reveal the reaper's weak point. Its other ability was to create massive storms and dark power at will but this ability was only briefly seen. The reaper would not even take a significant amount of damage to even being wounded at all (probably this is because the reaper could only be destroyed if the attack destroyed its weak point, which was armored by the lucky pants). On the lucky pants which covered the reaper's weak point, it's bottom, even if the attacks did not hit the lucky pants.

The lucky pants also made it virtually invincible to some of the most powerful attack sources on earth but only if the attacks were focused anywhere. It's abilities were being able to unleash waves of energy to assimilate kids (from both the shows Codename Kids Next Door and The Grim Adventures of Billy & Mandy, as well as several more Cartoon Network shows) in doing this, and being able to cut anything it struck. Numbuh 2 was the first victim to get assimilated. At the beginning of its creation, it consisted only Billy and the Delightful Children From Down The Lane, but soon started to grow as the Delightful Reaper began assimilating everyone else beyond. A giant Grim reaper-like figure that looks similar to grim but wearing the lucky pants and featuring the faces of disembodied skulls of everyone it has assimilated.

When Billy activates something, the resulting energies of the chamber fuses them together to create the Delightful Reaper. The fusion happens as the Delightful Children walks into the Delightfulization Chamber along with Billy who is wearing his dad's lucky pants and carrying Grim’s Scythe in the back. The Delightful Reaper was created by an accidental fusion of The Delightful Children From Down the Lane and Billy.

Billy grim reaper cartoon