The Suicide Bomb Sigil is a sigil that turns the user into a suicide bomb.
In an effort to break the Nephilim Jack, Michael lures him into a trap by abandoning his fortress and leaving Kevin Tran behind with the sigil branded into his chest. After delivering Michael's message, Kevin activates the sigil, killing himself, Jakob and the other two hunters with Jack. Jack is able to use his wings to shield Mary Winchester who survives as a result, but is knocked unconscious by the blast.
The sigil is branded into the skin of the user who activates it by hitting it with the palm of their hand. The sigil starts glowing a bright blue light which flashes a few times before turning the user into an explosion that consumes everything nearby, effectively making the user a suicide bomb. The explosion burns everything in its path, leaving anyone in the path of the explosion a charred corpse.