Death Field

You create a life-sapping region of negative energy, taking a toll on everyone inside it, including you. When you cast this spell, expend any number of your hit hit dice, up to your maximum; for each Hit Die spent in this way, roll the die and add your Constitution modifier to it. You take necrotic damage equal to the total (minimum of 1), and this damage cannot be reduced in any way, even if you normally resist or are immune to necrotic damage. Every other living thing within 60 ft of you must make a Constitution saving throw. Those who succeed escape damage entirely. Those who fail take the same amount of necrotic damage as you (though unlike you they may reduce it with any resistances or immunities they may possess). 

This spell has no effect on constructs or undead, nor can it be used by constructs or undead.