Corpsecrafter Master

You have mastered your ability to make superior undead soldiers and have learned how to cause your creations to channel dangerous amounts of negative energy through their bodies and weapons. However you learned these techniques you gain the following benefits: 

• Undead you create deal an extra 7 (2d6) necrotic damage with their attacks. This is a magical affect and is suppressed until you take a long rest if subjected to the affects of a Dispel Magic spell, or within the bounds of an antimagic field.
• When reduced to 0 HP, undead you create explode in a burst of negative energy dealing 10 (3d6) necrotic damage to all creatures except other undead in a 10 ft. radius around them. This damage is halved if a creature hit by the burst succeeds on a Con save using your spell save DC. This damage increases to 4d6 at level 17
• Undead you create are permanently subject to the Mage Armour spell. This is a magical affect and is suppressed until you take a long rest if subjected to the affects of a Dispel Magic spell, or within the bounds of an antimagic field.
• Skeletons and Zombies you create are permanently under your control, though other forms of undead still require castings of Animate/Create Undead to maintain control.

These benefits are not without cost however. When you enhance an undead you create using this feat, you must spend 1 of your hit dice to fuel the enhancement. As long as the undead you spend the hit die on is alive, you can't regain the spent hit dice by any means. Should the undead you created with this feat die or be destroyed, you can regain the spent hit dice as normal. Additionally as part of the spell used to create the undead enhanced by this feat you must also include powdered gems with a total cost of 25gp per your level as a material component that the spells consumes. These costs are in addition to any costs required by similar feats, such as Corpsecrafter Apprentice or Corpsecrafter Adept.

When you select this feat, undead you create have visible tendrils of necromantic energy coursing over their bodies. You choose how this energy appears but it must be obvious to a casual observer that the undead you create are charged with energy.