Celtic Sigil Trap
Celtic sigil traps are sigils that can be used to trap creatures. One version of the sigil trap is a variation of the triquetra, or Celtic trinity knot. For the spell to work, it consists of two sigils painted a distance apart, for example on opposite sides of a room. When one is activated by applying blood to the sigil, the person or creature located between the sigils will be forcibly drawn to the other and trapped there.
Bobby Singer knew of an old Celtic sigil that supposedly had the power to trap monsters. However, it never worked until he came across a soul eater.
11.11 Into the Mystic
Eileen Leahy learned a sigil spell from the hunter who raised her, Lillian O'Grady. She uses it to trap Sam when she thinks he is a banshee. Later she and the Winchesters use it to catch the real banshee.
11.16 Safe House
While trying to figure out how to stop a soul eater before it takes more victims, Bobby tells Rufus about a Celtic sigil that supposedly could trap any monsters. He tells him how it never worked before until a case in Goodlettsville, Tennessee, thinking it was a haunting he enters a home to find the hunter he was there to help, Harv, in a coma on the floor. Not knowing what else to do, he began drawing the sigil. Once he completed it, the house went back to normal, trapping the soul eater.
1.06 Art of Dying
Tracy Gellar had the triquetra variation painted on her living room wall. The Mac possessed soucouyant burns it off the wall before entering her home.