Bhut, Undead

Rot Aura. Any creature that comes within 10' of the bhut and has a sense of smell must make a DC 15 Constitution saving throw or take 15 (2d10+4) poison damage and be poisoned for 1 minute. If the target succeeds on the saving throw then it takes half as much damage, is not poisoned, and is immune to the bhut's rot aura for 1 hour.

Death's Door. When a living creature is reduced to 0 Hit Points or less by the undead bhut, the creature immediately receives a failed Death saving throw. If the creature dies, it will rise the next nightfall as an undead bhut unless resurrection or preservation magic is used to prevent the transformation.

Spellcasting. The [bhut] is a 5th-level spellcaster. Its spellcasting ability is [intelligence score] (spell save DC 14, +8 to hit with spell attacks). The [bhut] has following [wizard] spells prepared:
Cantrips (at will): [acid splash], [frostbite], [infestation]
1st level (3 slots): [disguise self], [cause fear], [magic missile]

2nd level (2 slots): [crown of madness], [ray of enfeeblement]

3rd level (1 slot): [bestow curse]

Multiple Attack. The bhut makes two attacks with its claws and one bite attack or it makes one foul spittle attack.

Claw. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 27 (4d8 + 9) [necrotic] damage and the target must make a DC 16 Constitution saving throw or the target has disadvantage on attack rolls made on its next turn. 

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 27 (4d8 + 9) [necrotic] damage and the target must make a DC 16 Constitution saving throw or the target is paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns to break the paralysis.  

Foul Spittle. RangedWeapon Attack: +9 to hit, range 40/90 ft., one target. Hit: 27 (4d8 + 9) [necrotic] damage and the target must make a DC 16 Constitution saving throw or be poisoned for 1 minute.