Cherubim

Aura of Knowledge. Any lawful-aligned creature within 600 feet of the Cherubim is given advantage on saves against being charmed and on WIZ, INT, and CHA saves. Chaotic-aligned creatures must a Wisdom saving throw (DC 15) or be subject to the effects of the confusion spell. Subsequent fails result in 1d4-1 points of psychic damage.   

Holy Sense. The Cherubim can detect any lie it hears without making a check. It cant make a lie itself.

Magic Resistance. The Cherubim has advantage on saving throws against spells and other magical effects. 

Spellcasting. The Cherubim is a 20-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 15, +8 to hit with spell attacks). The Cherubim has following cleric and wizard spells prepared:
At will: Thaumaturgy, Sending, Mind Sliver, Fog Cloud
5/day each: Control Winds, Blur, Antipathy/Sympathy, Dispel Magic                                      4/day each: Fear, Hallow, Mass Cure Wounds, Suggestion                                                      3/day each: Power Word Stun, Shatter, Reverse Gravity                                                          2/day each: Mass Suggestion, Meteor Swarm                                                                          1/day: Imprisonment 

Multiattack. The Cherubim makes and bite attack and one thunderous scream attack.

Bite. Melee Weapon Attack: +5 to hit, reach 10 ft., 1 target. Hit: 14 (3d6 + 4) piercing damage plus 1d4 radiant damage. If the target is large or smaller, it must make a strength saving throw (DC 14) or become grappled. It can repeat the save on it subsequent turns.   

Thunderous Scream. Ranged Weapon Attack: +8 to hit, range 120/120 ft., 1 target. Hit: The target must succeed a Wisdom saving throw (DC 15) or take 45 (10d8) psychic damage and be frightened of the Cherubim till the next round of action. While frightened in this way, they can not cast spells and make all actions at disadvantage.   

Gust.  The Cherubim chooses up to 10 creatures within sixty feet of it. They must make a strength saving throw (DC 15) or be pushed back 1d20+10 feet from the Cherubim by a powerful gust of wind. If they fail by a ten or less they are knocked prone. 

Change Shape. The Cherubim magically shape-shifts into a humanoid or beast that has a challenge rating equal to or less than its own, or back to its true form. Any equipment that the Cherubim is wearing is destroyed borne by its new form. In a new form, the Cherub's statistics are changed excepting its Thunderous Scream and spellcasting, along with it's CHA, INT, WIS, and CON.     

The Cherubim can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The Cherubim regains used legendary actions after 24 hours.

Cacophony of Light (Costs 2 Actions). The Cherubim expels a cloud of light in a 60 foot radius. The cloud is blocked by corners and objects larger than 5 ft. Any creature within this radius is blinded and deafened till the Cherub's next round, and can not take actions. 

Bite Attack. The Cherubim makes one bite attack.

Gust (Costs 2 Actions). The Cherubim makes one Gust action.