Relight my Fire is an achievement that requires the player to re-kindle the Dragon Forge.
Unlocking the mithril door on the upper level of Ancient Caverns grants access to the Dragon forge. This is unlocked using the Mithril key. This key is made by fusing together the strange key teeth with the strange key loop, items found during While Guthix Sleeps. The player can get the key fused by using either piece on a mithril dragon while have the other piece of the key in inventory.
Inside the mithril door are three hanging dragon heads and a giant orb in the centre. The player must click on each head to light it using Fire Wave spells, which will cause them to have fire to appear in their mouths and to slide towards the orb in the centre.