Shadowflame Apparition

The Shadowflame Apparition is an enemy summoned by the Goblin Summoner enemy during a Hardmode Goblin Invasion. Summoned in swarms as projectiles, they pass through blocks while attempting to ram into the player. They are immune to knockback, and both they and their caster move very quickly, allowing them to easily overwhelm the player.

Trivia

 * An is a name for a supernatural phenomenon, such as a ghost or phantom.  Terraria incorrectly spells it as apparation.