Here's another one that's prework for Machines of Bone & Blood! Pretty explicitly a replacement/rework of WotC's Way of the Long Death, a pretty underwhelming subclass published in the Sword Coast Adventurer's Guide.
First off, ignore the art, that's my standard placeholder art and this one will definitely be getting commissioned art. Second, I'm going to play with my format here a little bit; screenshots are above and a PDF is attached.
I didn't set out with a strict mechanical idea here: the Way of the Long Death this ~replaces is very much intended as a tanky monk, and the Rotting Hand can do that, but doesn't necessarily. It's much more driven by the theme than any mechanical plan.
Student of Death is our flavor and utility feature, granting darkvision, a save bonus against certain exploration hazards, and spiritcraft, which is the necromancer's utility cantrip. Rotting Curse is our damage feature — on a hit, you can expend 1 ki to set an enemy rotting. This does 3 martial arts dice of damage, which is a lot (and more than any other monk). But it doesn't trigger until the end of the enemy's turn, which is a big difference. Bleak Technique is mostly not an impactful feature, it just lets you convert your damage to necrotic for flavor's sake. Undead Affinity comes online at level 6, letting you put your study of the undead to good use. When you rest (or as a bonus action for a ki cost), you can select between Zombie, Ghoul, and Spirit. Zombies get much stronger death saves and the ability to spend ki to hop straight up. Ghouls get slightly increased damage and spending ki for temp hp. Spirits become incorporeal when they use Step of the Wind. And you get 1 extra ki per short rest to spend on these. Necromantic Acolyte at 11 gives you limited necromantic spellcasting and full immunity to necrotic damage. Take special note, these spells are chosen from the necromancer spell list — which is going to lose animate dead/reanimate in the next revision, so envision the feature without that. At 17, you achieve something resembling lichdom with Undying Discipline and Eternal Form. Undying Discipline lets you boost your stunning strikes to either paralyze or terrify. Eternal Form is infinite life.
As always, you're invited to come discuss and offer feedback in the comments or on Discord!