Cosmic talisman

The cosmic talisman is used to gain access to the cosmic altar. At the altar, players can craft runes out of rune or pure essence by using the runecrafting skill. It requires level 27 runecrafting to make cosmic runes at the altar. A cosmic talisman can be turned into a cosmic tiara by using the talisman on the altar while also having a tiara in your inventory.

Dropping Monsters
It is possible to get them as monster drops from abyssal guardians, abyssal leeches, Chaos Druid, ice giants, otherworldly beings, rock crabs, Salarin the Twisteds, abyssal walkers, green dragons, dagannoths, lesser demons, wallasalkies, Dagannoth Supremes, skeletal wyverns, giant rock crabs, and rock lobsters.