Essentia Resurrection

The caster carefully prepares four recently deceased Celestial, Dragon, Fey, Fiend, Giant, or Humanoid creatures that have died within the past day. 

The caster then uses the runed Siberys Dragonshard to pierce the temples of three of the deceased creatures, siphoning and destroying their soul, capturing the pure essentia. This shard is then driven through another creature three times, once through the temple, once through the throat into the brain stem, and once through the heart. The essentia is distributed amongst this creature, resurrecting the creature. 

When you cast this spell using a 3rd level spell slot, the corpses can be deceased for a week. Using a 4th level spell slot this increases to a month. Using a 5th level spell slot or higher this increases to a year.