Ancient Kendermore Black Dragon

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.

Sensitivity Aura. Attacks against creatures that do not have acid resistance or immunity within 10 feet of the dragon score a critical hit on a roll of 19 or 20.

Colossal. The dragon is considered Colossal sized (on grid: 60 ft. by 60 ft. or larger). This means that its hit dice are d20 + 5 [Example: 2d20 + (5 x CON modifier) + (2 x CON modifier)].

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: +17 to hit, reach 20 ft., one target. Hit: 24 (4d6 + 10) piercing damage plus 13 (2d12) acid damage.

Claw. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) slashing damage + 2 acid damage.

Tail. Melee Weapon Attack: +17 to hit, reach 25 ft., one target. Hit: 23 (2d12 + 10) bludgeoning damage.

Stinger. Melee Weapon Attack: +17 to hit, reach 25 ft., one target. Hit: 19 (2d8 + 10) piercing damage and the target must succeed on a DC 17 Constitution saving throw, taking 10 (3d6) acid damage + 13 (2d12) poison damage and be poisoned until the end of the next round on a failure, or half as much on a success.

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 19 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 95-­foot line that is 10 feet wide. Each creature in that line must make a DC 22 Dexterity saving throw, taking 99 (22d8) acid damage on a failed save, or half as much damage on a successful one.

Innate Spellcasting. The dragon's spellcasting ability is Charisma (spell save DC 20, +12 to hit with spell attacks). The dragon can innately cast the following spells, requiring only verbal components:

At Will: chill touch, shape water, darkness, create or destroy water, Melf's acid arrow

2/day each: fog cloud, scorching ray, blindness/deafness, virtrolic sphere, plant growth, hold monster, insect plague

Cruel Jest. As a reaction when a creature attempts to leave the dragon's reach, the dragon may force it to make a DC 21 Dexterity saving throw or be dragged 15 feet back towards the dragon. If the creature fails this save by 5 or more, this ability does not use the dragon's reaction.

Grasping Muck. As a reaction to being struck with an attack by a creature that is not flying, the dragon may force the attacker to succeed on a DC 19 Strength saving throw or be restrained until the end of the dragon's next turn.

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 22 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.

Mire. The dragon disturbs the earth around it. A creature that is not flying and ends its movement within 15 feet of the dragon begins to sink into the earth, and must make a DC 20 Strength saving throw. On a failed save, the creature has disadvantage on dexterity saves, has a -2 penalty to its AC, and can't make more than a single attack in a turn. These effects last until the end of the dragon's next turn.