Spike Ball

The Spike Ball is an indestructible enemy found in the Dungeon that swings around in a circle from a central pivot point (which also cannot be destroyed), and deals damage to the player on contact. Separate Spike Balls can have differing chain lengths. They spawn and despawn off-screen like any other enemy — if you leave a room and return later, it will have a different configuration of Spike Balls. They only appear in dungeon areas with a Brick Wall.

Tips

 * Placing a torch at the place where a Spike Ball swings through the floor or walls will allow players to keep track of its path.
 * Spike Balls only spawn in areas marked by the Marching Bones Banner.
 * The Mechanic (after rescue) and other NPCs will attack Spike Balls.
 * Pumpkins from The Horseman's Blade will follow Spike Balls.
 * Piranha from the Piranha gun can attach to the Spike Balls, however dealing zero damage.
 * The Leaf Crystal that hovers above the player when wearing Chlorophyte armor fires at Spike Balls.

Trivia

 * The Spike Ball, along with the Blazing Wheel, True Eye of Cthulhu, and the flying Golem Head are the only four invincible enemies in Terraria.

History
Spike Ball Булава на цепи