The Talisman is a magical sphere that holds the power of all worlds in it. It has the ability to heal people from illness and injuries, as well as allowing the travel between all possible worlds. The Talisman itself is similar to the Maerlyn's Rainbow. However, while Maerlyn's rainbow is evil in nature, the Talisman is good.
The Role in The Talisman
In The Talisman, Jack Sawyer seeks out the Talisman to save his mother from cancer. The Talisman was located in the Black Hotel. This building had some sort of magical protection around the building which prevents people from getting to the Talisman. Jack Sawyer eventually was able to fight off against the Black Hotels guardians and acquires the Talisman. In the final scene of the book, Jack heals his mom and the Talisman disappears.
The Role in Black House
In Black House, Jack Sawyer finds out that the power of the Talisman was transferred to him. With this power, he was able to help calm a mob of people and defeat Mr. Munshun.