Dullahan are feared throughout the land, and many see them as icons of death. However, they have one major weakness: Gold. The presence of gold cripples a dullahan, making them vulnerable to those who would rebel against death. Their weakness to gold is so overpowering that it takes major willpower from a dullahan simply to keep it on hand. 

You have vulnerability to bludgeoning, piercing, and slashing damage from gold plated weapons. If you are carrying or touching anything made of gold make a DC 15 Constitution saving throw or drop/release the item. Repeat this save every turn you carry the gold.

Dullahans have existed as headless reapers for as long as the oldest can remember. You cannot be killed by decapitation. You may attach or detach your head at will. You always know the distance and direction to your head unless it is on another plane.
Damage done to your head when separated reduces your hit points. When separate, both head and body can see and hear. Your headless body cannot speak but can eat and drink as well as cast spells, even spells with verbal components.

You count as one size larger when determining your carrying capacity and the weight you can push or drag.

In addition, any climb that requires hands and feet is especially difficult for you because of your equine legs. When you make such a climb, each foot of movement costs you 4 extra feet instead of the normal 1 extra foot.

You have hooves that you can use to make unarmed strikes. When you hit with them, the strike deals 1d6 + your Strength modifier bludgeoning damage, instead of the bludgeoning damage normal for an unarmed strike.

If you move at least 30 feet straight toward a target and then hit it with a melee weapon attack on the same turn, you can immediately follow that attack with a bonus action, making one attack against the target with your hooves.

Your fey connection to nature gives you an intuitive connection to the natural world and the animals within it. You therefore have proficiency in one of the following skills of your choice: Animal Handling, Medicine, Nature, or Survival.