Adult tungsten dragon

Ferrous sense. The tungsten dragon can sense and knows the exact location of any ferrous metals within 90ft of themselves.

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

Innate Spellcasting. The adult tungsten dragon's innate spellcasting ability is Wisdom (DC 15). The adult tungsten dragon can innately cast the following spells, requiring no material components:

3/day: zone of truth

Multi attack. The adult tungsten dragon uses its frightful presence, makes a bite attack and two claw attacks. 

Bite. Melee Weapon Attack: +11 to hit, reach 10 ft., 1 target. Hit: 16 (2d10 + 6) piercing damage. 

Claw. Melee Weapon Attack: +11 to hit, reach 5 ft., 1 target. Hit: 12 (2d6 + 6) slashing damage. 

Tail. Melee Weapon Attack: +11 to hit, reach 15 ft., 1 target. Hit: 14 (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 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.

Sand cloud (2/day). This effect is identical to the spell fog cloud but instead of fog its swirling sand. Within the area all flames are smothered even if its protected. Casters whist in the cloud must make a DC 15 Constitution check or lose concentration on any spell they are casting by the end of their turn. 

Sand breath (Recharges 5/6). The tungsten dragon exhales a blast of sand in a 60ft cone. Each creature within range must make a DC 18 Constitution saving throw or take 27 (9d6) bludgeoning damage and 27 (9d6) fire damage. Half as much damage on a successful save. 

The adult tungsten 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 adult tungsten 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 ft. of the dragon must succeed on a DC 18 Dexterity saving throw or take 12 (2d6 + 6) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.