B.R.A.N.D.A.

The Virus Released (Recharges after a Short or Long Rest). If the construct would be reduced to 0 hit points, its current hit point total instead resets to 200 hit points. Its body transforms into a raven-like stature with a long beak, metallic wings that are released from its back, and its feet become talons. While in this form the construct gains a flying speed of 50 ft. and does not provoke opportunity attacks when it flies out of an enemy's reach. Additionally, the construct can now use the options in the "Mythic Actions" section for 1 hour. Award a party an additional 11,500 XP (23,000 XP total) for defeating the construct after its Virus Released activates.

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

Immutable Form. The construct is immune to any spell or affect that would alter its form. 

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

Magic Weapons. The constructs weapon attacks are magical. 

Virus Regeneration. The construct regains 20 hit points at the start of its turn. If the construct takes damage from a silvered weapon or a spell, this trait doesn’t function at the start of the construct’s next turn. The construct dies only if it starts its turn with 0 hit points and doesn’t regenerate. 

Multiattack. B.R.A.N.D.A. makes three attacks with the piston hammer or fire bolt

Piston Hammer. Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit:  16 (2d8 + 7) bludgeoning damage plus 9 (2d8) force damage. 

Fire Bolt. Ranged Spell Attack: +7 to hit, range 120 ft., one target. Hit: 22 (4d10) fire damage.

Missile Eruption (Recharge 4-6). From a crystal in the palm of its hand a barrage of five arcane missiles fire out to targets of the construct's choice within 300 ft. Each dart does 10 (4d4) force damage.

Shield. The construct casts shield.

The construct 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 construct regains spent legendary actions at the start of its turn.

Strategic Flare. The construct casts expels a 15 ft. cone of fire from the crystal in the palm of its hand. Every creature within the cone must make a DC 17 Dexterity saving throw or take 17 (5d6) fire damage; or half as much on a success.

If the construct's The Virus Released trait has activated in the last hour, it can use the options below as legendary actions.

Bugged Teleport. The construct taps into a virus or a bug from its previous version and casts misty step.

Lycanthropic Strike. The construct makes a piston hammer attack at the closest target, flying there if need be. A target struck by this attack has to make a DC 17 Constitution saving throw or be cursed with wereraven lycanthropy.