Chaos Ball

This is not something that spawns. It is the attack thrown by goblin sorcerers and by Tim, and during a goblin invasion the Goblin Warlock circles you and streams them out without pause. The answer is always the caster: kill him and the balls stop, chase the balls and you will be there all night.

Internally this is an enemy rather than a projectile, with its own health and defense, and that changes how the fight plays. You can shoot one out of the air with anything that deals damage, which is genuinely useful when a warlock has filled the screen. The flip side is that homing weapons and minions will happily lock onto them and waste their output on ammunition instead of the sorcerer that keeps producing it.

It travels in a flat line at a steady clip and passes straight through terrain, glowing the whole way, so hiding behind blocks does nothing. What does work is movement. The path never adjusts once it is out, so a single step or a hop clears it as soon as you see it coming, and the light it gives off means you usually do.