Shadowflame Apparition

The Shadowflame Apparation is an enemy summoned by the Goblin Summoner mini-boss 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 apparition is a name for a supernatural phenomenon, such as a ghost or phantom. Terraria incorrectly spells it as apparation.