Minecraft wiki entry for Skeleton_Horse, associated text: The skeleton trap horse is triggered when a player comes within 10 blocks of it, resulting in a lightning strike that does not start fires or damage nearby entities. When struck, the skeleton trap horse transforms into a skeleton horseman: a skeleton, a stray or a wither skeleton riding a skeleton horse. It also spawns three additional skeleton horsemen in the vicinity. Each skeleton is equipped with an enchanted iron helmet and an enchanted bow, and has damage immunity for 3 seconds after spawning (in Bedrock Edition. Both horse and rider are immune to lightning).