Albarax, The Acidic Lord

Amphibious. The dragon can breathe air and water.

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

Acidic Bypass. Albarax, The Acidic Lord bypasses immunity and resistance to Acid

Albraxian Acid. Albarax, The Acidic Lord's acid damage cannot be healed by magical means unless all the acid is washed off the body and also does half of its damage as Max hit points damage which can only be restored after 3 long rests 

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

Bite. Melee Weapon Attack: +20 to hit, reach 25 ft., one target. Hit: 49 (6d12 + 10) piercing damage plus 22 (4d10) acid damage.

Claw. Melee Weapon Attack: +20 to hit, reach 20 ft., one target. Hit:  32 (5d8 + 10) slashing damage. plus 15 (3d10) acid damage

Tail. Melee Weapon Attack: +20 to hit, reach 30 ft., one target. Hit: 27 (4d10 + 10) bludgeoning 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 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.

Acid Breath (Recharge 5–6). The dragon exhales acid in a 90-foot line that is 30 feet wide. Each creature in that line must make a DC 28 Dexterity saving throw, taking 169 (26d12) acid damage on a failed save, or half as much damage on a successful one.

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 dragon 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 15 feet of the dragon must succeed on a DC 23 Dexterity saving throw or take 25 (4d10 + 10) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.