User blog comment:Crimson and Darkness/Volume 24 discussion blog/@comment-73.57.25.92-20171213224357/@comment-29963364-20171214004740

Unlike Human Magic, where you have to precisely control your Magic Power to "construct" certain effects, Devil Magic is where your imagination becomes real.

Examples:

1.) A Devil imagines "a fire-ball shoots out of my hand, and flies towards the opponent." Then they focus their Demonic Power into their hand, then release it, and their DP becomes the fire-ball, and flies toward the opponent.

2.) Issei imagines the women around him naked, then focuses & releases his DP, and the women's clothes get destroyed, "stripping" them naked.

You could say that Devil Magic is "using Demonic Power to enforce your desires upon reality."

Although, not all Devils have much talent for Magic. Some have to control their DP much like how Human Magicians do. This is why Issei initially has to touch his targets and snap his fingers to use [Dress Break].

The Devils of the Gremory Clan seem to be some of the ones with the most talent for Magic.


 * Sirzechs used all of his Magic Talent to master the [Power of Destruction] to the highest degree. He can freely control the PoD to only destroy his targets (to the point of non-existence), and can literally become an "Incarnation of Destruction."
 * Rias being able to use [Crimson Extinct Dragonar] and [Balor of Darkness] is likely due to her Magic Talent. She syncronizes her aura with Issei's/Gasper's, imagines herself in a powerful armor/form able to wield their power & abilities, and her DP makes it happen.