The Destroyer
The Destroyer is as previously stated, a big, long robotic worm. It is the upgraded version of the Eater of Worlds but unlike him, The Destroyer is way longer and no longer splits up if a segment is damaged. It is way more aggressive and faster. It also gains a LOT of firepower like each segment can launch a drone that shoots lasers at you.
Similar to the Eater of Worlds, weapons that can hit multiple times or have wide arcs are recommended.
Grenades or other explosives are also recommended due to their already high damage added with the damage to multiple segments.
Since this fight is a bit similar to the Eater of Worlds boss fight, remember not to get yourself trapped in its body when it attempts to cover you. If this happens though, try your best to avoid the body until it eventually hits you. Then, dart out of there while you still have the invincibility period from the hit and try not to get cornered again.
When you have taken damage, go after the probes / drones that fly around shooting lasers. These my drop hearts when killed. There is a limited amount of probes though. Each segment can only spawn one probe.
Just keep continuing the attack until eventually, you will have destroyed the Destroyer. Now you have stolen his title, you may gloat.. until someone or something strips you of it.