Minecraft wiki entry for Instant_Damage, associated text: Instant Damage inflicts magic damage of 3 × 2level. Undead mobs (including the wither) are healed as if with Instant Health instead. Death is reported as "<player> was killed by magic". When applied using a lingering potion, damage is inflicted every second. As this is magic damage, it can be decreased only via Resistance and Protection.‌[Java Edition only]