Poisonous Blood. A creature that hits the Wyrm with a weapon attack while within 10 feet of it takes 10(3d6) poison damage

Spellcasting.  The Wyrm can innately cast a few spells. Choose a number of spells of first level or higher from the divination school or that deal poison damage with a total combined level of 6. The Wyrm can innately cast those each of those spells once per rest at the lowest possible level with +9 to hit and a saving throw DC of 17.

Multiattack. The Wyrm makes two attacks: one with its bite and one with it's tail.

Bite. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 39 (5d12 + 7) piercing damage plus 10(3d6) poison damage.

Tail. Melee Weapon Attack: +12 to hit, reach 15 ft., one target. Hit: 29 (4d10 + 7) bludgeoning damage. If the target is a creature, it must succeed on a DC 20 Strength saving throw or be pushed up to 10 feet away from the Wyrm and knocked prone.

Poison Breath (Recharge 5–6). The Wyrm exhales poisonous gas in a 60-foot cone. Each creature in that area must make a DC 20 Constitution saving throw, taking 63 (18d6) poison damage on a failed save, or half as much damage on a successful one.