When you take damage, you can use your reaction to harden your blood-crystal veins, gaining resistance to that damage type until the start of your next turn.
You can use this feature once per long rest.

You carry within you faint memories and reflexes from the beings whose essence forged you. Once per long rest, you can gain advantage on one Arcana or Insight check you make. You must decide to use this feature before rolling.

Your blood remembers its origins and can subtly alter your physical state. When you finish a long rest, choose one of the following adaptations to manifest until your next rest:

• Reflexive Agility. You can take the Dash or Disengage action as a bonus action once per short or long rest.

• Keen Focus. You have advantage on your first saving throw against being charmed or frightened before your next long rest.

• Crystalline Flow. Your movement becomes unnaturally fluid. You can move through spaces as narrow as 6 inches wide without squeezing, and you have advantage on Acrobatics checks made to escape grapples or restraints.