Guide:Aquatic Scourge strategies

The Aquatic Scourge is a boss that is usually fought after defeating two Mechanical Bosses. The Aquatic Scourge will rarely spawn naturally in the Sulphurous Sea biome and can also be summoned using Seafood in the same biome.

This guide will mention items exclusive to Expert and Revengeance Mode with no special formatting and will follow the intended progression.

Terrain Preparation
Usually, it's wise to make three layers of platforms above your Sulphurous Sea, with the bottom layer about a block above the water. The platforms should have around 45 blocks of space in between each layer to accommodate for the Aquatic Scourge's size, projectiles and Sulphur gas clouds. Make sure that your platforms all stay within the Sulphurous Sea, as leaving the sea during the fight will cause the Aquatic Scourge to flee downward and despawn.

Armor

 * Titanium armor is an all-around good option for Melee, Ranged, and Mages due to its high survivability from Shadow Dodge.
 * Hallowed armor can also be utilized for extra damage. At least one of the mechanical bosses must be defeated first to obtain it, however.
 * Spider armor is generally preferred for Summoners due to the high damage bonuses for minions.
 * Daedalus armor is a well-rounded armor set for all classes. However, Cryogen must be defeated first to access it.

Accessories

 * Flame Wings and Frozen Wings are the best wings available to the player at this point, and should be prioritized.
 * The Butterfly Wings are a better choice for mage players due to the multiple bonuses.
 * A Frog Leg can be utilized with wings to give an extra boost to movement speed and vertical motion.
 * The MOAB (if available) can also be used but is generally more difficult to use effectively during this fight.
 * The Aero Stone can be used in conjunction with the MOAB to boost the effectiveness of each jump.
 * Frostspark Boots and Angel Treads (if available) are almost required for keeping up with Aquatic Scourge's fast movement speed.
 * The Evasion Scarf and the Shield of Cthulhu can be used to make quick dashes to escape deadly situations.
 * The Honey Dew or the Ambrosial Ampoule will increase survivability by increasing life regeneration and damage reduction, as well as providing immunity to the Venom debuff.
 * Melee players should use the Bloody Worm Scarf for its strong melee boosts as well as increased damage reduction.
 * If the player is utilizing Yoyos, then the Yoyo Bag should be prioritized.
 * Ranged players should use the Ranger Emblem to help in boosting damage output.
 * Magic players should use the Mana Flower and the Celestial Cuffs to quickly recover mana and the Sorcerer Emblem for extra damage.
 * Summoners can boost their minion damage with the Summoner Emblem.
 * Rogue users will find the Rogue Emblem and the Raider's Talisman useful to boost their damage output.

Weapons

 * It is sometimes preferable to fight the other bosses at this tier in progression to have a much wider array of options, some of which are listed below.

Melee

 * The Kelvin Catalyst is an extremely strong weapon due to its unlimited piercing ability, it can destroy the Aquatic Scourge but it is hard to craft.
 * The Ark of the Ancients' range and high DPS should make the fight fairly straight-forward for Melee users.
 * The Axe of Purity is a powerful yet risky weapon due to its low range.
 * The Trinity is a viable and easily obtainable option.
 * The Fetid Baghnakhs can decimate the Aquatic Scourge when paired with the Fungal Symbiote.
 * The Shimmerspark can also be utilized due to its decent range and falling stars.

Ranger

 * The Pearlwood Bow is an extremely powerful option with its rainbows.
 * The Daedalus Stormbow can decimate the Aquatic Scourge when paired with Holy Arrows.
 * The Darkecho Greatbow paired with Jester's Arrows is a direct but powerful option.
 * The Dart Pistol paired with Cursed Darts can prove a powerful force, especially if the dart trails can constantly land hits.
 * The Megashark and the Butcher can deal decent damage to the Aquatic Scourge when paired with Frostspark Bullets.
 * The Star Cannon can be quite good against it due to its infinite piercing, although it might be tedious getting stars.
 * The Titanium Railgun can be effective due to its high damage and piercing.

Mage

 * The Poseidon is usually the best overall choice dealing good damage due to its piercing typhoons.
 * The Nimbus Rod can be used to gain extra DPS on the Aquatic Scourge's segments.
 * The Serpentine can tear through the Aquatic Scourge when paired with the Deific Amulet.
 * The Relic of Ruin is extremely viable for this fight due to its homing and damaging blades.

Summoner

 * The Black Hawk Remote is extremely effective against the Aquatic Scourge because of its targeting system, letting you focus on dodging instead of re-summoning your minions.
 * The Ancient Ice Chunk is extremely effective at dealing damage to the Aquatic Scourge and its summons.
 * The Mounted Scanner is another very effective option for the Aquatic Scourge.
 * The Cryogenic Staff can provide additional DPS to your minions.
 * The Shellfish Staff can latch onto the Aquatic Scourge to deal powerful damage over time.

Rogue

 * The Kelvin Catalyst is an extremely strong weapon due to its unlimited piercing ability, it can destroy the Aquatic Scourge but it is hard to craft.
 * The Gacruxian Mollusk is a powerful option that can work on everything in the entire fight.
 * The Spear of Paleolith when fired upwards can deal massive damage to the Aquatic Scourge due to its fossil shards.
 * The Prismalline can deal good damage to the Aquatic Scourge, and can quickly take care of its summons.
 * The Brimblade's ability to stack can rack up large amounts of damage against the Aquatic Scourge.
 * Adamantite Throwing Axes can destroy the Aquatic Scourge in seconds, especially when paired with the stealth strike bonus of the Titan Heart armor.

Miscellaneous

 * The Well Fed buff provides a useful all around stat boost.
 * Farm Blood Orbs to easily craft many helpful potions that will increase your survivability.

The Fight
The Aquatic Scourge fight differs based on the player's game mode. Due to this, Revengeance, and Death Mode fight breakdowns will be separate from the main breakdown.

In Normal and Expert Mode
The Aquatic Scourge will spawn offscreen and will initially be passive. Dealing around 500 damage to it will start the fight. The Aquatic Scourge will charge towards you very quickly, but turns slowly to compensate. It will occasionally "vomit" out various projectiles that will deal massive damage to you if you get hit. The various projectiles are:
 * Sulphuric water bolts which travel quickly in a straight line.
 * Tooth-like projectiles which home in on the player.
 * Sulphur gas clouds that linger in the air for a long time.

The Sulphuric water bolts will explode on contact with any blocks and shouldn't be much of a hassle to deal with. The tooth projectiles will loosely home in on you for about 10 seconds before despawning, a simple change in direction should throw them off enough to miss you. The Sulphur gas clouds will hinder your ability to make a specific turn again, so keep in mind where they are during the fight. The Aquatic Scourge will also occasionally spawn in Aquatic Parasites, Aquatic Seekers, and Aquatic Urchins to harass you throughout the fight, make sure to keep a close eye out for them as they will disrupt your movement.

Various loops and circles should be utilized to effectively dodge all of its projectiles, but the Aquatic Scourge moves fast, so keeping up with its speed should be the main priority during the fight. The Aquatic Scourge's acceleration is quite poor and it struggles to make sharp turns, so use that your advantage when trying to avoid it. A well-timed dash may also save you from damage in certain situations.

The Aquatic Scourge has no second phase. Thus, the same steps should be repeated until you've defeated it.

Avoid flipping Gravity as it will cause the Aquatic Scourge to gain a massive speed boost, easily killing you, but it does make Aquatic Scourge turn even slower to compensate.

In Revengeance Mode
The Aquatic Scourge in Revengeance mode is a much more formidable opponent compared to the previous two game modes. The Aquatic Scourge overall gains a massive speed boost and projectile velocity increase; making it a challenge, especially with limited mobility. The best way to avoid the Aquatic Scourge with these changes is to utilize a dashing item more frequently. The main goal of the fight should still be to avoid the Aquatic Scourge itself. Tanking the fight is discouraged.

While performing loops and circles still works to an extent, it's best to move in patterns that can allow you to avoid the gas clouds and summons when rebounding.

At 50% health, the Aquatic Scourge preforms a new spin attack, where it will temporarily stop chasing you to fire a volley of projectiles. It's unwise to focus down the Aquatic Scourge unless using a piercing weapon during this attack. The spin attack should be used as a moment to re-align yourself and give you a break for a few seconds. After performing a spin attack, the Aquatic Scourge will return to chasing you.

In Death Mode
While in Death Mode, the Aquatic Scourge gains another boost to its movement speed and projectile velocity, an additional 10 body segments, and its tooth projectiles home in towards you much more aggressively. Also, all attacks are available to the Aquatic Scourge at all times. This is both good and bad for you, as it means you get a break more often from the spin attack, but otherwise you are always being chased by both the Aquatic Scourge and the tooth projectiles that sharply home-in on you. Dashing accessories can become almost mandatory because of this.

When confronted with a barrage of multiple waves of sand blasts and tooth projectiles, do not be afraid to slow down and carefully maneuver the barrage, as the Aquatic Scourge is usually recovering from its spin attack during that time. Just be prepared to quickly exit that situation as soon as the Aquatic Scourge closes in on you.

General Tips

 * It is advised to fight the Aquatic Scourge in the daytime, as the sulphuric gas clouds can be difficult to spot at night.
 * The Rod of Discord is a very useful tool as it allows instantaneous teleporting to avoid the numerous projectiles.
 * The Lunic Eye, Golden Gun, and the Golden Shower are not needed for this fight as the Aquatic Scourge is immune to Ichor and Marked.