Shapechanger. Virtos can use its action to polymorph into a drake-humanoid hybrid or into a drake, or back into its true form, which is humanoid. Its statistics, other than its AC and Size, are the same in each form. Any equipment it is wearing or carrying isn't transformed. It reverts to its true form if it dies.
In it's full drake form Virtos became Large size.

Keen Hearing and Smell. Virtos has advantage on Wisdom (Perception) checks that rely on hearing or smell.

Multiattack. Virtos makes two attacks: two with its claws (Hybrid form) or one with its bite and one with its claws (Drake form).

Bite (Drake or Hybrid Form Only). Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 9 (1d10 + 4) piercing damage, or 13 (2d8 + 4) piercing damage if used in Drake Form.

Claws. (Drake or Hybrid Form Only). Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.

Poison Bolt (Recharge 5–6). Virtos exhales a compressed poisonous bolt in a 40-­foot line that is 10 feet wide. Each creature in that line must make a DC 14 Constitution saving throw, taking 35 (10d6) poison damage on a failed save, or half as much damage on a successful one.

Virtos can take 2 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. Virtos regains spent legendary actions at the start of its turn.

Detect. Virtos makes a Wisdom (Perception) check.

Poison Aura (Costs 2 Actions). Virtos expell gas from his back. Each creature within 5 feet of Virtos must succeed on a DC 14 Constitution saving throw or take 13 (3d8) poison damage and be blinded for 1 round by the poison cloud.