Blood Frenzy. Strahd has advantage on attack rolls against a creature that doesn’t have all its hit points.

Echolocation. Strahd can't use his blindsight while deafened.

Misty Escape. When Strahd drops to 0 hit points, he transforms into a cloud of mist (as in the Shapechanger trait) instead of falling unconscious, provided that he isn’t in running water or sunlight. If he can’t transform, he is destroyed.

While he has 0 hit points in mist form, he must reach his coffin within 2 hours or be destroyed. Once in his coffin, he reverts to his vampire form. He is then paralyzed until he regains at least 1 hit point. After 1 hour in his coffin with 0 hit points, he regains 1 hit point.

Shadows of Vampyr. Strahd is surrounded by flame-like shadows, which make him heavily obscured to others. The shadows turn dim light within 20 feet of it to darkness, and bright light in the same area to dim light. While the flames persist, Strahd has resistance to radiant damage and regains 20 hit points at the start of his turn. In addition, whenever a creature within 10 feet of Strahd hits him with an attack, the shadows lash out at that creature, dealing 4d8 (18) necrotic damage to it.

The flames can dispelled (DC 19) or suppressed by an area of antimagic. While the flames are active, Strahd is immune to the harmful effects of sunlight.

Shadow Stealth. While in dim light or darkness, Strahd can take the Hide action as a bonus action on his turn.

Sunlight Hypersensitivity. While in sunlight, Strahd takes 20 radiant damage at the start of his turn, and he has disadvantage on attack rolls and ability checks.

Multiattack. Strahd can use Frightful Presence. He then makes three attacks: one with his bite and two with his claws. Strahd can replace each of his attacks with one use of Fling.

Bite. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 21 (2d10 + 10) piercing damage plus 14 (4d6) necrotic damage. The target’s hit point maximum is reduced by an amount equal to the necrotic damage taken, and Strahd regains hit points equal to that amount. The target dies if its hit point maximum is reduced to 0. A humanoid slain by this attack rises instantly as a vampire spawn under Strahd's control.

Claw. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 17 (2d6 + 10) slashing damage. If the target is a Huge or smaller creature, it is grappled (escape DC 20) and restrained until the grapple ends.

Fling. Strahd hurls one creature he is grappling up to 60 feet in a direction of his choice. The target lands prone, taking 3 (1d6) bludgeoning damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 20 Dexterity saving throw or take the same damage and be knocked prone.

Frightful Presence. Each creature of Strahd's choice that is within 120 feet him and aware of him must succeed on a DC 22 Wisdom saving throw or become frightened for 1 minute. While frightened in this way, a creature is also paralyzed. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to Strahd's Frightful Presence for the next 24 hours.

Caustic Breath (Recharge 5–6). Strahd vomits caustic blood in a 90-foot line that is 10 feet wide. Each creature in that line must make a DC 24 Dexterity saving throw, taking 91 (26d6) acid damage on a failed save, or half as much damage on a successful one.

Children of the Night (Recharge 5-6). Strahd magically calls 2d12 swarms of bats or swarms of rats, provided that the sun isn’t up. While outdoors, Strahd can call 3d6 giant bats instead, or he can summon Argynvost the dracolich. The called creatures arrive in the next round, acting as allies of Strahd and obeying his telepathic commands. The beasts remain for 1 hour, until Strahd dies, or until he dismisses them as a bonus action.

Strahd can take 3 legendary actions, choosing from the options below.

Claw or Fling. Strahd makes a claw attack or uses Fling.

Children of the Night. Strahd uses his Children of the Night ability. 

Indomitable. Strahd ends one negative effect currently affecting him. He can use this action even while incapacitated or otherwise unable to take actions.

Bite (Costs 2 Actions). Strahd makes a bite attack. 

Burning Blood (Costs 2 Actions). Strahd targets a creature within 60 feet of him, magically causing its blood to boil in its veins. The target makes a DC 22 Constitution saving throw, taking 28 (8d6) fire damage on a failed save, or half as much damage on a successful one. At the end of each of its turns, the target repeats the saving throw, taking 14 (4d6) fire damage on a failed save, or ending the effect on a successful one.

Wing Attack (Costs 2 Actions). Strahd beats his wings. Each creature within 15 feet of him must succeed on a DC 25 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. Strahd can then fly up to half his flying speed without provoking opportunity attacks.

Stunning Screech (Costs 3 Actions). Strahd emits an ear-shattering screech. Each creature within 60 feet of him that can hear him must succeed on a DC 22 Constitution saving throw or take 30 (5d8 + 8) thunder damage and be stunned and deafened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to Strahd's Stunning Screech for the next 24 hours.