True Eye of Cthulhu

You never go looking for these. One spawns the instant you destroy an eye on the Moon Lord, meaning the two in his hands and the one in his head, and it then orbits him while chasing you with the same attacks it was using before it came loose. You cannot kill it. By the time his core is finally open there are three of them in the air, so the closing stretch of the fight is the most dangerous part despite having the least health left in front of you. They only leave when he dies, or when everyone in the world does.

Their attacks run in a fixed order: paired bolts, a sphere volley, a ring of homing eyes, a sweeping ray, then a second sphere volley. Watch it twice and you already know what is coming for the rest of the fight, which is most of the battle solved.

Because the loop is fixed, the moment you free each one decides whether you are reading one pattern or three staggered ones. Break the hands and head at random times and you get a constant stream with no gaps anywhere in it. Instead, hold each part just above death and finish it during the sphere volley that closes the cycle. All three then move through the loop in step. Three volleys landing at once looks worse on paper, but it gives you a single pattern to read and genuine quiet between attacks.

• The bolts aim where you are going rather than where you are, so flying a straight line feeds them. Cut sideways as they launch and they pass behind you.
• The sphere volley arrives as one spread with nothing to dodge individually. Be moving before it commits.
• The homing eyes need a moment to lock on. Once they have, they turn slowly, so climbing beats trying to outrun them.
• The ray sweeps an arc rather than firing a line. Backing away does nothing inside the cone; get out to the side of it.

Every part of this is a movement problem, so mobility accessories pay double. Master Ninja Gear is the standard pick for the speed and the occasional free dodge it hands you. Two curiosities: they carry a health value and even a death sound despite being unkillable, and hitting one with a minecart can actually make it disappear.