The Soul talisman is an unreleased Runecrafting item that will most likely allow players to enter the Soul Altar. It can be seen but it is not obtainable. It will probably be possible to combine the talisman with a tiara to make a Soul tiara at the Soul Altar and with a Runecrafting staff to make a Soul talisman staff.
An image of the Soul talisman was discovered on the Jagex website via URL manipulation, leading many at the time to believe Soul rune crafting would be made available quickly. Jagex responded to the discovery by removing the Soul talisman image from the website. The Grand Exchange Database also contained images of the Soul talisman, but have since been removed by Jagex. With the release of the wicked hood there is an option for a teleport to the Soul Altar, meaning that a Soul Altar is likely to be coming soon. Furthermore, there is a rift in the Abyss reserved for bringing players to the Soul Altar, however, players are currently unable to use it.
Since the release of the Runespan, the release of the soul altar is very likely. In the Runespan, there are Soul esswraiths requiring 90 runecrafting to siphon, which will likely be the level required to make soul runes, since all the essence creatures match the runecrafting level to siphon.