Flow Invader

The Flow Invader is an enemy that spawns near and is summoned by the Stardust Pillar during the Lunar Events. When it spawns, three smaller minions will appear one at a time and begin orbiting it. The Flow Invader uses these as attacks, sending them as 1-2 high speed projectiles towards the player. When it die, it will shoot 3 projectiles as a final attack. The orbiting minions reappear over time. It will launch all remaining minions at the player upon death. If the Flow Invader is killed shortly after it spawns, less minions will be launched at the player.

Trivia

 * It seems to resemble a bluer miniature version of the Moon Lord's head.