The Goblet of Blood is a chalice used as a common form of communication between demons and their allies such as the Four Horsemen of the Apocalypse, but is not limited to them. The angels can use it as well, but grudgingly and only as a last resort. It is one of the many items featured in the Supernatural television series.
DescriptionThe Goblet of Blood itself is a rather large silver or brazen in color. It depicts numerous distorted faces, possibly that of demons or humans in pain.
The goblet requires blood from a human, although it is later revealed that dog blood could be used as well. This is usually procured fresh, most commonly from the slit throat of a victim. Once the goblet is filled with blood, the user recites a Latin incantation, "Tire quiero patem me a di" and stirs the blood. The contents of the goblet then lights up and/or bubbles, indicating the goblet is ready for use. The goblet is sometimes depicted with a matching knife of similar design and color. However, it has been shown that the blood does not necessarily need to be spilled by use of a special knife.
This method of communication is very effective and appears infallible. It can work over large distances, and even through different dimensions, such as from Earth to Hell. As a magical object, it still functions even when used on an alternate reality where magic does not exist or is not usually useable.
Talking to Pestilence appeared to require a chant dedicated to the Horseman. Brady used the following incantation, "Dis manibus praest praesens obtine mihi dominum. Pestilentiarum omnimum'. A fly emerged from the goblet once the incantation was recited, indicating Pestilence answered the call.
Crowley has shown the capability to create a similar form of communication using only blood. When he was bound by Sam as part of the third trial to close the gates of Hell, Crowley bit Sam in the arm. Once he was out of view, Crowley spat out the blood he acquired into his palm and uttered a Latin incantation, allowing him to send a message to all demons without having to use a goblet. The following incantation is "Inferni sectatores, nunc audite regem".
This method is similar to the one using a goblet, in that it is not affected by negation of spells. Crowley was bound with several demonic handcuffs and was trapped within a devil's trap and yet was able to send a message without fail, much like how Virgil successfully used a Goblet of Blood from an alternate reality that is devoid of any form of magic. However as Crowley sent it out more akin to an SOS, it's implied he is unable to direct it at any one.
In beginning of the episode "Black", after torturing one of Crowley's demonic girls, Sam forced her to call forth Crowley via another alternate version of this method, however, he used a common plastic cup rather than the goblet.