Anvil No More is a master combat achievement which requires the player to kill Tekton before he is able to use the anvil a second time.
Defence-draining weapons such as the bandos godsword or dragon warhammer are recommended for this achievement due to their accuracy and ability to hit high. Tekton will automatically return to the anvil if no one is in range when he scans or after attacking for a while, restoring some of his health and drained stats in the process. Try to avoid forcing Tekton returning to the anvil as it will reduce the amount of hits the team can land.
Tekton is weakest to crush attacks so using an elder maul, or inquisitor mace is recommended, with a zamorakian hasta/dragon hunter lance as last-ditch alternatives. Inquisitor's armour helps complement the crush-based style with accuracy and damage bonuses, which should help deal plenty of damage to Tekton if he has been successfully debuffed.