Aqua Event

The Aqua Event is caused by Solar Cultist if you have already killed moonlord. It causes parts of the world to be flooded and you have to kill a certain amount of water enemies to remove the water. To remove the water, you have to use a drop from the Solar Cultist: The Drain.

Each flooded part represents parts of the worlds water: Crimson/Corruption flood, Purity flood, Desert flood, and Hallows flood. Once you destroy all of these floods, the text "impenetrable destruction rises..."

After a minute, it says "Cthulhu has awoken!" Cthulhu is a boss that has its eyes as a mob simular to the True Eye of Cthulhu; True Twins. These however, can be killed. The true twins both has 40k health. There is also the True Brain of Cthulhu which however, cannot be killed. You have to hurt the head by 45k health and a certain part of Cthulhu will be gone. The arms have the ability to spawn in clones of Solar Cultist. The wings are an optional thing to hurt, as it will make it easier to fight without the wings.

Once you hurt the arms, eyes, and brain, Cthulhu will die. He will drop items that deal with water.