Spinal Healing Injector

Spinal Healing Injector is an tinker enchant (only usable by players with Engineering) to belts. It can be used to increase the mana gained from using a Mythical Healing Potion. As such, this is by no means a "free" healing potion - it will only work if there's a Mythical Healing Potion in the player's inventory to consume. This also means it triggers and is affected by the potion cooldown.

Source
This tinker is learned through Discovery; it can be randomly learned when making a Cataclysm-related item in Engineering.