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Medium undead, chaotic evil
Stench. Any creature that starts its turn within 5 feet of the ghast must succeed on a DC 10 Constitution saving throw or be poisoned until the start of its next turn. On a successful saving throw, the creature is immune to the ghast's Stench for 24 hours.
Turning Defiance. The ghast and any ghouls within 30 feet of it have advantage on saving throws against effects that turn undead.
Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 12 (2d8 + 3) piercing damage.
Claws. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 3) slashing damage. If the target is a creature other than an undead, it must succeed on a DC 10 Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
See 5e SRD:Ghouls.