Foul Form (5e Spell)
From D&D Wiki
|Casting time:||1 action|
|Components:||VSM (the fingerbone of an undead, engraved with jewels worth at least 500gp)|
You cause your form to adapt to the evil energies of the multiverse. For the duration, your skin appears to be decaying, you give off a sickening stench, and bile and slime ooze from your pores. While in this state, whenever you would take poison or necrotic damage, you take no damage, and instead regain hit points equal to half of the damage you would have taken before resistances and immunities. Any effect that would heal an undead creature also heals you.
You may communicate with undead creatures through rudimentary telepathy and body language, regardless of whether you speak the same language, and undead creatures with 14 or less Intelligence will not automatically attack you unless they are commanded to. Finally, for the duration, you may move freely through oozes and slimes, taking no damage in the process.
The average person will not interact with you in this state; on a failed DC18 Intelligence (Investigation) check, a creature will believe you are undead and will react accordingly.
At Higher Levels. When you cast this spell using a spell slot of 8th level, the duration increases to 1 hour, and with a spell slot of 9th level, it increases to 24 hours.