Crystal horn is an item used in the Princess and the Warrior. It is only obtained as a drop from a crystal dragon during and after the quest. It is used as one of the components to turn the Death altar into a Life altar. The life altar has a number next to it's name, which should show how many charges the altar has till it turns back into a death altar. Every time a Life rune is crafted, one charge is consumed. One crystal horn (along with a death talisman and 100 Nature-, Cosmic-, Exile- and Astral runes) grants 100 charges to the Life altar.