Doctor Octopus' Tentacles

Otto Octavius built the tentacles to do work his hands could not. A sustained fusion reaction needs adjustments at a scale and a speed no human arm manages, so he made a set of them: artificially intelligent mechanical limbs, driven from a harness across his back, with a neural inhibitor chip in the rig to keep their intelligence away from his own higher brain functions. Each arm runs four and a half feet long, reaches out to thirteen, and lifts three tons. Heat does not trouble them and neither does magnetism. The claw at the end of each opens into a spike when force is wanted, or into a fine tweezer for work that has to happen a millimeter at a time.