As an Enderman one of the most common substances in worlds that contain life is your biggest enemy. Whenever you make contact with water, examples would be getting caught in the rain, falling into any body of water, or drinking it, this includes anything that contains water as an ingredient. You may use a reaction to use your Teleport feature to reach an unoccupied dry space. Otherwise take 2d4 acid damage at the start of each turns for as long as you have contact with water, if you ingest water this only happens once. 

Your Dexterity score increases by 2, and Your Constitution score increases by 1 .

The exact lifespan of an Enderman is unknown, it could be many thousands of years or only a century. (this is ruled by the dm.)

Enderman tower over most humanoids with only the shortest endermen being around equal to the tallest humanoids. Enderman range from 8 to 13 feet and have slender builds. Your size is Medium.

Your base walking speed is 30 feet.

Accustomed to the darkness of the end, 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 speak, read, and write Common and Enderman. Enderman is a distorted, almost garbled, version of Common, most but not all endermen know common some only know enderman.