Deathsinger

Deathsingers are both heralds of death and agents of it.  They chant an ancient song with words of power that brings an end to those who are destined to die.

Deathsong

Beginning at 2nd level, you can use a bonus action to begin chanting a song.  You must use a bonus action each turn for one minute to continue chanting. A creature does not recognize this effect is magical or harmful by default. As an action it can attempt an Arcana check against your spell save DC to determine the nature of the song. If you do not finish your song, you do not expend your use of this ability. At the conclusion or the song, choose any number of creatures, other than constructs or undead, that were within 60 feet of you for the duration of the song. These creatures must make a Wisdom Saving throw against your spell save DC, taking 1d12 psychic damage and gaining one level of exhaustion on a failure and taking half damage and no exhaustion on a success.  This damage increases to 2d12 at 6th level in this class, 3d12 at 10th level, and 4d12 at 14th level. If this damage reduces a target to 0 hit points, it dies instantly and cannot be returned to life by a spell of seventh level or lower.  You can use this ability again once you finish a long rest. If you kill a creature with this ability, you regain its use. You can regain it this way a number of times per long rest up to your intelligence modifier.

Deadly Spells

Starting at 6th level, the first time a creature fails a saving throw against one of your wizard spells of 1st level or higher with a verbal component, you can deal psychic damage equal to your intelligence modifier to the creature.

Harbinger of Death

Starting at 10th level, you can use your action to summon a Banshee at a point within 60 feet of you. This banshee rolls its own initiative, is friendly to you and your companions, obeys your commands and, remains for 10 minutes or until it is reduced to 0 hit points.  You regain this ability when you finish a long rest.

Words of Power

Starting at 14th level, when a creature fails its saving throw against your death song, it dies instantly if it has 20 hit points or less after applying the psychic damage. Additionally, add Power Word Pain to your wizard spell book if it is not already there. When you use a spell slot to cast a Power Word spell (such as Power Word Pain, Power Word Stun, or Power Word Kill), you can regain a spell slot of a level lower than the slot expended. The spell slot you regain cannot be higher than 5th level.