Minecraft wiki entry for Mob, associated text: Some mobs are weak or immune to certain kinds of damage. Sea creatures, such as turtles, take more damage from tridents that are enchanted with Impaling.‌[Java Edition only]‌[until JE Combat Tests] Skeletons and their variants are immune to drowning. All undead mobs are healed by potions of Harming, but take extra damage from weapons enchanted with Smite, along with taking damage from Potions of Healing. Many of these weaknesses and immunities are a result of what category (see below) of mobs that the mob falls into.