A construct left long abandoned beneath the earth. A malfunctioning artifact harvested from the ruins of a wizard's tower. A strange device falling in from another place and time. You have made a deal with a powerful synthetic being. Whatever inhuman desires drive it, you are obliged to fufill. What enemies stand against your mechanical master will find themselves faced with an implacable foe. Strike after strike, you will evade their blows. Spell after spell will break against you. Their flesh will be broken down and repurposed into your strength. Even if they should strike you down, with a crackle of electricity you rise once more to turn the tide. And when the fight seems lost, devour the world and leave behind nothing but gray dust. 

Expanded Spell List

Additional spells are added to the warlock spell list for you 

Combat Analysis

Starting at 1st level, when a creature that you can see makes an attack roll against you or forces you to make a saving throw you can use your reaction to analyze the opponent

• If the triggering effect is an attack, you add a bonus to your armor class equal to half your proficiency bonus (rounded down)
• If the triggering effect is a saving throw, you add a modifier to your saving throw equal to half your proficiency bonus (rounded down)

You can use this feature a number of times equal to your charisma modifier and this resets after a  long rest. 

Designed Resilience

Starting at 6th level, your patron has granted you significant mechanical augmentations. You gain resistance to lightning damage and when you take damage, you may use your reaction to expend one warlock spell slot and recover health equal to 1d10 per spell level of the slot expended. If the damage reduces you to zero hit points, you may do so with expending a warlock spell slot. Once you use this feature in this way, you must take a short or long rest before using it again. 

Organic Resource Reclamation

Starting at 10th level,  when you use your Combat Analysis reaction, the creature that triggered the effect must make a constitution saving throw with a DC equal to your warlock spell save DC. On a failure the creature takes 2d4 force damage, or half as much on a success. You gain temporary hit points equal to half the damage taken  (Reminder: temporary hit points do not stack). 

Gray Goo Protocol

Starting at 14th level, as an action you can unleash a wave of tiny drones to devastate an area. You can force all creatures within a 30 foot radius of a point you can see within  60 feet of you to make a constitution saving throw with the DC equal to your spell save DC. On a failure, a creature takes 5d10 force damage, and half as much on a success. Nonmagical weapons, armor and items are consumed and destroyed by the swarm. The swarm then returns to you and recover hit points equal to the damage rolled.