* [[7.01 Meet The New Boss]]: The Winchesters and Bobby obtain a binding spell from [[Crowley]] and use it to bind [[Death]]. One of the ingredients of the spell is [http://en.wikipedia.org/wiki/Fulgerite fulgerite] an object formed when lightening fuses the silica in sand together. While Death is bound to them, Castiel cannot kill Sam and Dean. It is Castiel who frees Death.
===See Also===
*[[Binding Link]]: used to bind a Demon inside a Human.
*[[Death]]