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

Improved Critical. if the angel rolls a 19 or 20 it is a critical hit.

Multiattack. The angel can use its greatsword 4 times.

Greatsword. Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: 21 (6d6 + 7) slashing damage plus 18 (3d10) radiant damage.

Change Shape. The angel magically polymorphs into a humanoid that has a challenge rating no higher than its own, or back into its true form. It reverts to its true form if it dies. Any equipment it is wearing or carrying is absorbed or borne by the new form (the angel's choice).

In a new form, the angel retains its alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary Resistance and Intelligence, Wisdom, and Charisma scores, as well as this action. Its statistics and capabilities are otherwise replaced by those of the new form, except any class features or legendary actions of that form.

The angel 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 angel makes a Wisdom (Perception) check.

Wing Attack (Costs 2 Actions). The angel beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 25 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage plus 12(3d6) fire damage and be knocked prone. The dragon can then fly up to half its flying speed.