A blue Firemaking tome is a experience reward from the minigame, Temple Trekking. You can get one by taking one of the easy followers to Paterdomus or to Burgh de Rott. At the end, you will get a Reward token (blue) which you can exchange by clicking on the first option, Claim-reward. The Firemaking tome grants Firemaking experience once read, and the blue version will give 1100-1650 Firemaking experience.
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