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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.
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.