Warpwood is a peculiar species of tree that are only found in the Towering Wood, deep within the Eldeen Reaches. Despite many efforts, no one has successfully managed to get them to grow anywhere else. They are a creation of the Avassh, the Twister of Roots, but much like Brightwort, they seem to be entirely benign.
When a warpwood seed is planted into the stump of a missing limb, the tree that grows from that seed will form a fully functional wooden prosthetic that perfectly matches the lost limb, with all of its capabilities. There is distrust among some in the Wood about whether these prosthetics are safe, perhaps well founded given the origin of the tree, but to date there has never been a reported case of any kind of rejection, or any limb going rogue.