Tofanis the Corrosive

Amphibious: The dragon can breathe both air and water.

Legendary Resistance (3/day): If the dragon fails a saving throw, it can choose to succeed instead.

Actions

Multiattack: The dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Bite: Melee weapon attack: +11 to hit, reach 10ft, one target. Hit: 16 (2d10+5) piercing damage + 5 (1d10) acid damage.

Claw: Melee weapon attack: +11 to hit, reach 5ft, one target. Hit: 12 (2d6+5) piercing damage.

Tail: Melee weapon attack: +11 to hit, reach 15ft, one target. Hit: 14 (2d8+5) piercing damage.

Frightful Presence: Each creature of the dragon's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 17 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.

Acid Breath: The dragon exhales necrotic energy in a 60-foot line that is 5 feet wide. Each creature in that line must make a DC 17 Dexterity saving throw, taking 28 (8d6) acid damage on a failed save, or half as much damage on a successful one. Creatures who fail their save continue to take half as much damage again at the end of each of their turns for 1 minute. A creature can use an action to scrape away the acid on themselves or a another creature within their reach.

Sleep Breath: The dragon exhales narcotic vapors in a 30-foot cone. Each creature in that area must succeed on a DC 17 Constitution saving throw. On a failed save, the creature falls asleep. A sleeping creature can repeat the save at the end of their turn, and they wake up if it takes any damage, or if another creature uses its action to shake it awake.

Legendary Actions

The dragon can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The hydra regains spent legendary actions at the start of its turn.

Detect: The dragon makes a Wisdom (Perception) check.

Tail Attack: The dragon makes a Tail attack.

Wing Attack (Costs 2 actions): The dragon beats its wings. Each creature within 10 feet of the dragon must succeed on a DC 17 Dexterity saving throw or take 14 (2d6+7) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.