The Reaper Class for D&D Fifth Edition

Well, I've been mulling this thought in my head for a good long while, but today, in a fit of creativity, I made a full draft of the Reaper class for D&D.

Inspired in part by the Death Knight from World of Warcraft, the Reaper deviates significantly from both that design as well as the Oathbreaker Paladin and similar Death Knight designs.

The most distinguishing feature of the class is that a character who becomes a Reaper is now considered undead. This severely limits the ways in which the Reaper can be healed by friendly magic, but to aid in their survival, they have a number of ways to heal themselves in the midst of combat.

Reapers are a martial class, with access to martial weapons, heavy armor and shields, the extra attack and level 5, and a number of aggressive fighting styles.

They eventually learn to imbue their weapons with power to deal extra necrotic damage and then special runes that cause additional damage and other effects.

Like Paladins and Rangers (and Artificers, now,) Reapers are half-casters who can have up to 5th level spells.

Reapers have three subclasses, called Sigils, which are the Sigil of Blood, Sigil of Death, and Sigil of Shadow.

Blood Reapers focus on battlefield tactics and enhanced self-healing.

Death Reapers focus on spellcasting, summoning an incorporeal minion and learning more spells as well as cantrips to allow them to act as true ranged casters.

Shadow Reapers focus on stealth and instilling fear in their foes, gaining the ability to move stealthily even wearing heavy armor and gaining various bonuses against frightened opponents.

I created a spell list for them that blends some of the Paladin's and Wizard's spells (particularly Smite spells, necromancy, and illusion spells.) I also created an old WoW favorite, Corpse Explosion, which is just as nasty and horrible as it sounds.

Naturally, this being the first truly finished draft of the class means that there are likely a lot of kinks to work out. I have no idea if it's balanced - I suspect it's overpowered until I look at some of the high-level Paladin abilities and then I wonder if it's underpowered.

Being unable to heal up from Cure Wounds or most other healing spells feels like it could be a dealbreaker to anyone considering the class, so I wonder if the healing solutions I've come up with are good enough (much of it is based on being able to spend hit dice in the middle of combat, but I worry that that'll just make short rests less useful to Reapers, rather than actually making up for the lack of most magical healing.)

Still, I'm fairly pleased with this ambitious concept. Naturally I'm also worried that I've come up with too-complicated mechanics, but I think in the end it shouldn't be unmanageable.