Ice Elemental

Ice Elementals are Hardmode enemies that hover towards the player and shoot blasts of ice, which have a chance to inflict the Chilled debuff. They are immune to almost all debuffs. They can appear in the Underground Snow Biome at all times, and on the surface at night.

Trivia

 * Elementals are magical entities who embody/personify a force of nature. Historically, elementals personify one of the four Classical elements: earth, water, air or fire (sometimes plant, but never Aether). Dungeons & Dragons introduced elementals that were fusions, and other unconventional elementals.