The Destroyer

The Destroyer is a hardmode version of Eater of Worlds boss, which was introduced in the 1.1 patch. It is summoned using a Mechanical Worm.

'The Destroyer has a metallic-like body unlike Eater of Worlds which has a corrupted worm body. The Destroyer has red lights in its body. Those lights are Probes that The Destroyer sends out. If the light isn't lit up, that means Probe was already launched from that segment. Left over parts of Probes are able to return to empty segments and possibly restore.

Unlike other worms, all segments of The Destroyer share his total health, meaning you damage all segments even if you only hit one. Unlike the Eater of Worlds it does not split in to segments. Therefore The Destroyer contains all of his awesome length, and in combination with his shared health it makes him an easy target to hit, perfect pillow for pins.

Due to its massive health, it seems almost impossible to kill The Destroyer without end-game weapons.

You can spawn The Destroyer only at night, so make sure you can get him down before morning.