Blightwyrm

Aberrant Lungs. The blightwyrm does not need to breathe and takes no damage from toxic gas.

Vengeance. If a creature knocks out the blightwyrm with a melee attack and no more than 30 damage left over and is within 15 feet of it, the blightwyrm makes a bite attack against the creature who knocked it out. If its breath weapon is recharged, it may make a breath attack again, but the range is reduced to a 15 foot cone and the target has +2 on saving throws. After this attack, the blightwyrm is knocked out.

Bite. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 19 (2d10 + 8) piercing and 15 (2d8 + 6) poison damage.

Stinger (Recharge 3–6). Melee Weapon Attack: +9 to hit, reach 15 ft., one target. Hit: 13 (2d8 + 4) piercing and 7 (2d6) poison damage. The target must succeed in a DC 13 Constitution Saving Throw or be paralyzed.

Horrifying Presence. Each creature of the blightwyrms's choice that is within 120 feet of the blightwyrm and aware of it must succeed on a DC 26 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dragon's Frightful Presence for the next 24 hours.

Breath Weapons (Recharge 5–6). The dragon uses one of the following breath weapons.

Anti-Diviner Breath. The dragon exhales anti-magic in a 60-foot cone. Each creature in that area must make a DC 24 Dexterity saving throw, taking 27 (5d10) force and 27 (5d10) poison damage on a failed save, or half as much damage on a successful one. Any creature using concentration on a spell in the area of the cone must succeed in a DC 15 Wisdom Saving Throw or break concentration. Additionally, each time a creature hit by the anti-magic who casts a divination spell before the end of the Blightwyrms next turn takes 9 (2d8) psychic damage.

Blightfire Breath. The dragon exhales gray-red fire in a 60-foot cone. Each creature in that area must succeed on a DC 24 Constitution saving throw or take 38 (7d10) fire damage. Additionally, creatures who fail the saving throw gain 1 level of exhaustion and have disadvantage on Constitution saving throws for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

The blightwyrm can take the burrow legendary action once and only at the end of another creature's turn. The blightwyrm can't use it again until the start of its turn.

Burrow. The blightwyrm burrows underground and resurfaces up 30 feet away. This does not provoke opportunity attacks, and if the blightwyrm resurfaces up within 5 feet of a creature, the blightwyrm may make a bite attack.