Corrupted Dragon of Eshu

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

Curse of Eshu. every 30 seconds the dragon shifts between elements, changing its form and its traits to resemble other dragons of that type (including resistances)

1d10 is rolled to determine the dragons type every 5 turns (30 seconds)

1.  black dragon.  acid breath, 60ft line, 5ft wide. amphibious, breathe both water and air
2. copper dragon. acid breath, 60ft line, 5ft wide. slowing breath, 60ft cone, DC18 con saving throw, or be unable to use reactions, move at half speed, only one attack, can only use a bonus action OR an action, lasts 1 minute, check can be rerolled at start of each turn
3. blue dragon. lightning breath, 90ft line, 5ft wide.
4. bronze dragon. lightning breath, 90ft line, 5ft wide. repulsion breath, 30ft cone, DC19 Con saving throw or be thrown back 60ft. amphibious, breathe both water and air
5. Red dragon. fire breath, 60ft cone. 
6. Brass dragon. Fire breath, 60ft line, 5ft wide. sleep breath, 60ft cone, DC18 con saving throw, or fall unconscious for 10 minutes
7. Gold dragon. Fire breath, 60ft cone. Weakening breath, 60ft cone, DC21 strength saving throw or have disadvantage on Strength-based attack rolls, Strength checks, and Strength saving throws, lasts 1 minute, check can be rerolled at start of each turn. amphibious, breathe both water and air
8. Green dragon. 60ft cone. amphibious, breathe both water and air
9. White dragon. 60ft cone. 
10. Silver dragon. 60ft cone. paralyzing breath, 60ft cone, DC20 con saving throw or be paralyzed, lasts 1 minute, check can be rerolled at start of each turn 

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 10 ft., one target. Hit: 17 (2d10 + 6) piercing damage plus 4 (1d8) (whatever element they are) damage.

Claw. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) slashing damage.

Tail. Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 15 (2d8 + 6) 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 16 Wisdom saving throw or become [condition]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 weapon (Recharge 5–6); The dragon exhales their breath. Each creature in that line must make a DC 18 Dexterity saving throw, taking 54 (14d6); (whatever element they are) 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 10 feet of the dragon must succeed on a DC 19 Dexterity saving throw or take 13 (2d6 + 6) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.