The Cup is a gilded; glassine chalice carved from Adamas and dipped in gold, and is the size of an ordinary wineglass, though heavier.

Because of its inexplicable transformative powers, drinking from the Cup turns humans into Shadowhunters. It became sacred and magical after Raziel used it as the vessel for his blood, imbuing it with his vast angelic power.

However, drinking from the Cup has its risks and does not always work. The Cup sometimes decides to be a stubborn and refuses to share its power with people (or share too much power). Thus, while drinking from the cup, some mundanes are unable to support the power given to them by the cup and turn into horrifying corpses. Because of this, only specially selected mundanes are allowed to drink from the Mortal Cup, since many never survive the transition. Mundanes are evaluated before they can drink from the cup and Ascend.

The cup also gives Shadowhunters the special ability to control demons.

A few years before the mortal cup had been stolen by You Know Who, it was used for creating new Shadowhunters. Ask your elders about it.

After Valentine's invasion and (rumoured) death, it was, according to the clave, under heavy protection.

Later it was found in a deck of cards. It was cleverly disguised in there by Jocelyn Fray, Valentine's wife. But what about the Clave saying it was under 'heavy protection?' We don't know. Go figure.

Article by starcrossedlovers_06