Dank Octopus

The Dank Octopus is a War Mode mini-boss that spawns in the Ocean. It spawns with a 10% chance to spawn every in game hour. When the player encounters a Dank Octopus, it will start shooting music notes that deal three quarters of its damage. These notes also have a homing mechanic. Once a Dank Octopus reaches 50% HP it gains triple defense and glows white like the Wither from minecraft. At 25% HP it becomes immune to any arrow types. In expert mode and above it gains 50% damage reduction too. In master mode, at 5% HP it shoots its notes more and constantly regenerates 1 Hp. It also gains 85% damage reduction. It seems like just an enemy, but one of its drops, Mysterious Skin, is required to craft the Mysterious Tear, which summons Phantoghast.