D&D 5E List of instant death spells in 5e

[Fanaelialae]

Inflict Wounds does damage by inflicting wounds. It's right in the name. You would notice that all of their skin was rotting off from necrosis.

In fairness, a generous DM might allow the player to inflict internal injuries with necrotic damage, thereby giving the appearance of no injury (assuming the absence of forensic science).

That's why the best approach would be to simply discuss it with the DM (or if you are the DM, make a ruling).

 

[Langy]

You may be looking for anything that does Psychic damage, like Dream. Those shouldn't leave any sort of physical mark except, possibly, blood coming out of the nose/eyes/ears.

 

[Croesus]

Check out the night hag in the MM. It's Nightmare Haunting ability might be what you need.

 

[Saeviomagy]

Stab them to death, then cast mending on the body.

 

[Iain_Coleman]

Stab them to death, then cast mending on the body.

Ooh, sneaky.

 

[Langy]

Stab them to death, then cast mending on the body.

I may need to remember that for my campaign!

 

[mellored]

Drown them and dry them out (create or destroy water).

True polymorph them into a corpse.

A bluff check, followed by feign death.

Magic Jar.

Astral Projection.

Poisons damage might also work, like cloud kill.

 

[Mull Ponders]

Stab them to death, then cast mending on the body.

And don't forget Prestidigitation to clean up the blood.

 

[Reynard]

Stab them to death, then cast mending on the body.

Nice!

Also cast Gentle Repose to confound investigators as to the time of death.

 

[jaelis]

True polymorph into a corpse?