You can separate your head from your body. As an action you can pick up and move your head unhindered and it takes a free action to drop your head. Your head has A third of your total health, cannot move and can only cast spells with Somatic components. (Any spells with Somatic components are cast from your head.)

The body keeps two thirds of your total health and can only move 30ft away from your head, the body cannot cast any spells with Somatic components. Once your body moves 30ft away you must make A Wisdom save DC 5 (plus 2 for each 5ft the body moves away) to maintain control. Once you lose control of your body it can no longer cast spells, make ranged attacks and the body will begin to act as A normal zombie treating any living creature as an enemy.

• Your body gains its own Initiative.
• Your body cannot be affected by any spell requiring an Intelligence save, Wisdom save and Charisma save.
• Your body has Undead Fortitude, once it hits 0 Hp make A Constitution save DC 5+Damage and on a success come back to 1 Hp.
• You can cast any spell without Somatic components from the body.
• Your body doesn't need to make death saves once it hits 0 Hp.

Once your body fails its Undead Fortitude save it will be unconscious until you take a long rest or is healed by A healing spell. Out of combat You can control and feel your body up to 60 ft regardless of line of sight however once your body is 150ft away you lose all contact.

Your Constitution score goes up by 2, and your Wisdom and Charisma score go down by 1

Dullahans being undead don't age but rather run out of vengeful energy towards 300 or so years. Once one runs out of this energy they slowly lose consciousness forever. Being resurrected resets this timer. 

Dullahans are usually very curious because of their lack of memories and usually don't have many prejudices towards good or evil. However their first impression of people usually affect their outlook on others, if the first people they meet swindle them out of their money they become more reserved and less trustful or if the first person they meet treats them with kindless and hospitality they might end up kinder and more welcoming.

Because of Dullahans' undead position their height ranges from 3-5 feet to 7-8 feet. The size is determined from the previous life, ranging from Small to Large.

Your base walking speed is 30 feet.

Accustomed to twilit forests and the night sky, you have superior vision in dark and dim conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.

As an undead creature you are vulnerable to Radiant damage.

You have advantage on Animal Handling checks.