While in sunlight, the Damphir has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.

You bite a willing or unconscious creature, or make an attack roll against a defending creature, to bite into their skin. 
On a successful hit you roll damage, and as part of the attack you can drink the blood of a creature. Gaining temporary hit points equal to the damage you have dealt.

If you drink blood 10 times before you take a long rest, gain a +1 your strength, dexterity and constitution checks and saving throws.
If a creature has had their blood drunk 10 times before they take a long rest, they gain one point of exhaustion. 

Your vampiric glamor makes you a sight to behold, and charming in the eyes of those you speak to.
Once per long rest, you gain the ability to cast Charm Person.

Your Charisma score increases by 2, your Dexterity score increases by 1.