The omni-talisman is a project of Wizard Elriss's, who can be found in the Runecrafting Guild. You can help her by showing her every talisman. By doing this she can create an Omni-Talisman for you. The Omni-Talisman is a single talisman that contains the properties of all the other talismans, so essentially it's 12 talismans in 1. This means you can visit every runecrafting alter to create runes by carrying only the Omni-Talisman (or an item created from the talisman).
The talisman can be used to create and Omni-tiara or an Omni-talisman staff, both of which can be used to visit every runecrafting alter just like the source, the Omni-Talisman. To craft an Omni-talisman into a tiara or staff, take it to Wizard Korvak, who can be found staggering about in the Runecrafting Guild, jumping at shadows and being generally terrified of everything.
If the Omni-talisman is lost for any reason (including combining it with a tiara, staff or Wicked hood), a new one may be obtained by speaking to Elriss. The talismans don't need to be shown to her again to get a replacement.
The talismans to give Elriss are: Earth, Air, Fire, Water, Body, Mind, Chaos, Law, Nature, Cosmic, Death, and Blood. Elriss will give you runecrafting experience for each of the twelve talisman shown to her, as shown in the table below, for a total of 13, 605 runecrafting experience gained. You don't need to show the astral or soul talisman as they're not yet created in game, and although the elemental talisman is in game you don't need to show it to her.Runecrafting Experience Gained