|Well, congrats. You discovered it. You get to name it.|
Although this article is based on canonical information, the actual name of this subject is conjectural.
An Energy Focusing Sigil is a sigil that magnifies light and energy. This sigil can also be used as a bomb when drawn on celestial beings. If an angel uses it as a bomb, the sigil will magnify the light and energy of the angel and create a massive explosion capable of destroying anything in a certain radius.
In Stairway to Heaven, Oren, Constantine and Tessa used this under brainwashing from Metatron to kill rival angelic faction leaders to bring their followers under his leadership rather than Castiel's. Gadreel later used this in Do You Believe In Miracles? to free Castiel from Heaven's dungeon, sacrificing himself to do so. This (as well as many other new sigils) have only been shown in season 9, so it is possible that they were hidden from all the angels with the exception of Metatron and might have been written on the angel tablet.
The sigil must be placed somewhere on the vessel of the angel (and possibly other beings), either by being tattooed on, or carved into the flesh. Once the sigil is placed on them, it exposes them to earthly objects and weapons, making them lethal to the angel. They must then stab themselves on the sigil, causing their grace to explode out of their vessel, creating a massive explosion destroying everything in the radius of the sigil. Any other angels directly in the explosion's path are atomized and any humans are killed. However, Gadreel survived this explosion while protecting Metatron but was severely hurt by it though he may have been far enough away as it wasn't targeted on Metatron but Tyrus. Alternate Kevin Tran was able to magnify the energy of his soul and used it to blast a multiple hunters with an intense beam, killing everyone except for Jack and Mary who blocked it with his wings.
- This spell maybe closely related to demon bomb at some points (or maybe shared some similar characteristics and mechanisms). Except, this spell can affect anything, even human and building near it, like conventional bomb, while the Demon Bomb only affects demons in a certain radius.
- Tessa, who is a reaper, is also able to use this spell. Although it has never been tested, as Dean stopped her and destroyed the sigil before she was able to use the spell.
- If there are humans residing in the area where an angel kills him/herself, they will be mass-smote.