Azazle The Cold-Iron Tyrant.

Fear Aura. Any creature hostile to Chrono The Iron Tyrant that starts its turn within 30 feet of him must make a DC 22 Wisdom saving throw, unless he is incapacitated. On a failed save, the creature is frightened until the start of its next turn. If a creature's saving throw is successful, the creature is immune to his Fear Aura for the next 24 hours.

Spellcasting. The Iron Tyrant is a 20-level spellcaster. Its spellcasting ability is Charisma (spell save DC 23, +15 to hit with spell attacks). The Iron Tyrant has following Paladin spells prepared:

Cantrips (at will): Light, Firebolt

1st level (4 slots): Shield of Faith, Cure Wounds, Bane, Hellish Rebuke, Inflict Wounds, Command, Compelled Duel.

2nd level (3 slots): Darkness, Find Steed (Giant Nightmare), Crown of Madness, Locate object.

3rd level (3 slots): Aura of Vitality, Animate dead, Bistow Curse, Spirit Shroud, Blinding Smite.

4th level (3 slots): Death Ward, Locate Creature, Staggering smite.

5th level (2 slots): Banishing Smite, Geas, Destructive Wave. 

Divine Smite. The Iron Tyrant can use the Paladins Divine Smite feature.

Lay on Hands. The Iron Tyrant has a pool of 100 hit points that it can use as an action to heal one creature that it touches up to the maximum amount remaining in its pool (excluding constructs and undead).

ArchDukes Ribspreader. The Iron Tyrant has a +1 bonus to AC from the "Archdukes Ribspreader" minor properties, as well as resistance to cold. (Included in the stats)

Major properties. The Iron Tyrant can use an action to cast one 7th-level spell from the Archdukes Ribspreader. After you cast the spell, roll a d6. On a roll of 1-5, you can't cast it again until the next dawn. (Divine Word)

Defense. The Iron Tyrant has the Defense fighting style giving it a +1 bonus to AC

Divine Sense. The Iron Tyrant has the Paladins Divine Sense feature.

Aura of Protection. The Iron Tyrant along with any other friendly creature of its choosing within 30ft of it gains a bonus to saving throws equal to its Charisma modifier (+ 7). It must be conscious to grant this buff.

Aura of Hate. The Iron Tyrant, as well any fiends and undead friendly to it within 10 feet, gain a bonus to melee weapon damage rolls equal to your Charisma modifier (+7). A creature can benefit from this feature from only one paladin at a time

Dread Lord. The Iron Tyrant can, as an action, surround itself with an aura of gloom that lasts for 1 minute. The aura reduces any bright light in a 30-foot radius around it to dim light. Whenever an enemy that is frightened by it starts its turn in the aura, it takes 4d10 psychic damage. Additionally, you and any creatures of it's choosing in the aura are draped in deeper shadow. Creatures that rely on sight have disadvantage on attack rolls against creatures draped in this shadow.

While the aura lasts, it can use a bonus action on its turn to cause the shadows in the aura to attack one creature. Make a melee spell attack against the target. If the attack hits, the target takes necrotic damage equal to 3d10 + your Charisma modifier.

Radiant Hatred. The Iron Tyrant deals an additional 6d8 radiant damage on each of its melee weapon attacks (Included in the attack). 

Cleansing Touch. The Iron Tyrant can use an action to end one spell effect on itself or one willing creature that it touches. It can use this feature a number of times equal to its Charisma modifier.

Shield Master. The Iron Tyran has the "Shield master" feat.

Multiattack. The Iron Tyrant makes two attacks with it's Holy Avenger.

Ribspreader. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 25 (2d8 + 17) Slashing damage. Plus an additional 24 (6d8) Radiant damage.

Shield Bash. Melee Weapon attack: +18 to hit, reach 10 ft, one target. Hit: 23 (2d6 +17) bludgeoning damage. Plus an additional 24 (6d8) Radiant damage. On a hit the creature must make an athletics contested by the Iron Tyrants or fall prone and be knocked back 15ft.

Flame Burst (Recharge 5-6). The Iron Tyrant explodes into a burst of flames, each creature in a 30 foot sphere centered on the Iron Tyrant must make a DC 21 Dexterity saving throw or take 63 (18d6) fire damage. Any creature killed by this is destroyed along with any nonmagical items it was carrying.

Shield (1/day). The Iron Tyrant casts the shield spell.

Shrivel and Dull (4/day). When the Iron Tyrant is the target of an attack, It can use it's reaction to block the attack with it's wings. Roll 4d4 and subtract the total off of the attack roll.

The Iron Tyrant takes 2 legendary actions, choosing from the options below. One legendary action can be used at a time and only at the end of another creatures turn. The Iron Tyrant regains spent legendary actions at the start of its turn.

 Holy Avenger or Sheild Bash. (Costs 1 Action). The Iron Tyrant uses one of its attack actions.

Control Feind or Dreadful Aspect. (Costs 1 Action). The Iron Tyrant uses one of its Channel Divinity options.

Immolating Gaze. (Costs 1 Action) The Iron Tyrant turns his magical gaze towards 1 creature he can see within 120 feet of him and commands it to combust, the creature must succeed a DC 23 Wisdom saving throw or take (28) 5d10 Radiant damage.