Ancient Soldier Dragon

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

Spellcasting. The dragon is a 2nd-level spellcaster. Its spellcasting ability is 5 (spell save DC 2, +9 to hit with spell attacks). The dragon has following Fighter spells prepared:
Cantrips (at will): true strike, message, fire bolt. 
1st level (4 slots): cause fear, shield, thunderwave, magic missile.

2nd level (9 slots): continual flame, darkvision, magic weapon, earthbind, flaming sphere, misty step, gust of wind, knock, scorching ray, .

Multiattack. The dragon makes two melee attacks.

Bite. Melee Weapon Attack: +9 to hit, reach 20 ft., 1 target. Hit: 12 piercing damage and 6 fire damage.

Claw. Melee Weapon Attack: +9 to hit, reach 20 ft., 1 target. Hit: 11 slashing damage

Tail. Melee Weapon Attack: +9 to hit, reach 30 ft., 1 target. Hit: 13 bludgeoning damage. 

Wing Attack. Melee Weapon Attack: +9 to hit, reach 20 ft., 1 target. Hit: 10 bludgeoning damage.

Armor Bash. Melee Weapon Attack: +7 to hit, reach 15 ft., 1 target. Hit: 17 bludgeoning damage. The creature being attacked must roll a d20. If the attacked creature rolls any number above 5, than it is knocked prone. 

Static Fire Breath. RangedWeapon Attack: +8 to hit, range 40/80 ft., 1 target. Hit: 35 fire damage and 11 lightning damage.

Defensive Strength. If there are any creatures attacking the dragon's allies, than the dragon will magically give 2 of it's allies resistance to the type of damage it is taking for 4 turns. The dragon then loses 3 hit points in exchange for helping it's allies.