Guide:Queen Slime strategies

Spawn Conditions
Queen Slime can be summoned by using a in The Hallow, which is found in the Underground Hallow in the same places that  spawn.

The Fight
In her first phase, Queen Slime jumps around in a similar fashion to King Slime, though much faster. She periodically summons Crystal Slimes, Heavenly Slimes, or Bouncy Slimes. Crystal slimes will shoot several crystals upwards, heavenly slimes will fly towards the player and bouncy slimes will fire bouncing shots towards the player. After a few jumps, she does one of two things, chosen at random:


 * Will stay in one place for a few seconds, before jumping very quickly towards the player and attempt to stomp them, dealing high damage.
 * Will stay in one place for a few seconds, before firing 6 Regal Gel that bounce twice before breaking. Sometimes, she will perform this attack multiple times in a row.

Killing the smaller slimes should be a priority during this phase, as they can quickly overwhelm the player.

When at 50% health, Queen Slime will grow wings and begin to fly like a Slimer. Her AI also changes:


 * She will occasionally shoot  Regal Gel in 10 directions.
 * She will occasionally attempt to fly above and drop down onto the player.

Terrain Preparation
Queen Slime shoots out bouncing projectiles that can be a challenge to dodge, especially in the second stage. Fighting in an off-ground arena with platforms on the bottom will allow the projectiles to fall out safely. For example, a Sky Bridge consisted of platforms is extremely recommended. If you have Lava Waders or its upgrades, it may be a good idea to use bubble and lava instead of platforms, as the neither the Queen Slime in the first phase nor the slimes she summons can stand on them. This will come at the cost of slowing down each time the player moves through the lava.

Armor

 * or is helpful for all classes.
 * If you have already defeated a Mechanical Boss, the set is extremely effective for all classes due to its  effect. This allows the player to avoid some of the many projectiles the Queen Slime spawns, negating a large amount of her damage.
 * Summoners and Mages can use.
 * Melee and Ranged classes can use.

Weapons
It's important to have weapons that can deal with the crowd of slimes that she summons, as well as weapons that can reach her in her winged form.


 * For Melee users


 * The it's good because of its accuracy and several projectiles
 * The or . or  if you already defeated a Mechanical Boss. are good yoyos because of their high damage


 * For Ranged users


 * The or  with  is useful due to its high damage output and its semi-homing ricochet ability, which can kill all of the nearby slimes that are summoned.
 * The, while also being useful for killing the smaller slimes, can still do a hefty amount of damage to the Queen Slime when paired with / and a.


 * For Magic users


 * The is highly useful in this fight, as with most Hardmode boss fights, for its defense-lowering ability, although as a penetrating weapon, it is also reasonably useful on its own for clearing out the slime minions.
 * The is a high damage weapon that can be used for most bosses at this point in the game, but it uses a lot of mana very quickly, so a lot of mana potions will be required (except perhaps in the second phase, where if the player is able to take out the many minion slimes quickly, there will be many mana stars available for pickup).
 * The can provide some additional DPS against all targets. Casting it immediately before starting the fight is a decent option, as it does not constantly drain mana and its clouds linger for a significant duration.
 * The is a decent choice all around, being able to hit Queen Slime herself easily as well as effectively deal with her slime minions, although it is a bit harder to aim properly in the second phase.
 * The deals very high damage, but is only really useful in the second phase: During phase one, it is too hard to control which enemy it targets, often hitting a slime minion instead of Queen Slime herself (or vice-versa). In phase two, it becomes useful against Queen Slime if you can follow her closely, as the minion slimes are far less likely to be right next to her when she is flying.
 * The can deal high damage to the Queen Slime because of her large size, but it will not deal with the smaller slimes well.
 * Some weapons which are best suited for close-quarters are less useful in this fight, as keeping a safe distance from Queen Slime is paramount for Magic users:
 * The cannot poison the boss nor her slime minions, and while it deals respectable damage still, its limited range makes it an unwise choice for use against the boss, and its inaccurate spread makes it hard to use against the small minion slimes.
 * The also deals respectable DPS, but its projectiles are inaccurate and somewhat range-limited, and even considering their ability to ricochet, with so many small and/or fast-moving targets this weapon is of limited use compared to others.
 * The dropped by  can deal good damage to Queen Slime and the slimes she summons because of its piercing ability. However, its short range makes it extremely dangerous to try to use against the boss herself, as it leaves the player too open to her melee attacks.


 * For Summoners
 * The is the highest damage summon weapon available at this point in the game if no mechanical bosses have been defeated, but obtaining it requires a lot of luck, and it may be easier or wiser to forego it in favor of more easily-obtainable options.
 * The is effective, since it can pierce through 25 defense and the Queen Slime only has 26, but it is not as effective against the slimes that she summons because they have higher defense. It is most effective with the because of its tag damage.
 * The can be used as alternative that requires less grinding to get, although the  is a formidable enemy in its own right.
 * The can help quite a lot with dealing with the many minion slimes, depending on where you place its sentries.
 * Whips may not be very good options for attacking Queen Slime herself, as their somewhat limited range can put players in danger of her melee attacks, but they can be extremely useful in taking out the various minion slimes.
 * The deals good damage, and its snowflake minion (which ignores enemy defense) is quite helpful for fighting the minion slimes, which have high defense but low health.
 * For players who have defeated a Mechanical Boss already, the is another good option, with its melee-speed-increasing buff and even higher damage.
 * The is considerably less useful for killing the smaller slimes, because of its lower damage compared to their considerable defense.

Accessories
There are many great accessories available at this point.


 * The (or any of its upgrades such as the ) will make the variety of attacks much more survivable.
 * ,, or  are the best wings available at this stage, but  are reasonable substitutes.  or better will provide better ground movement.  are also can also be used because they increase the ascent speed of wings. Those two accessories will allow you to move almost freely through the air and on the ground.
 * The or its upgrades prevents knockback and it is practically mandatory for melee users, but useful for any class.
 * The is a defensive accessory that reduces damage if your health starts getting low. The Expert mode exclusive  is also effective.
 * The enhances survivability by providing regeneration and reducing the duration of Potion Sickness. To reduce the potion cooldown, it only needs to be equipped during the instant a health potion is drunk.
 * An Emblem provides additional damage for your primary damage type;
 * Yoyo fighters should use a, as it doubles a yoyo's damage output, as well as providing 2 extra counterweights that can do a bit more damage.
 * should be used if using a or any Repeater with /.
 * Magic users who wish to rely less on Mana Potions can equip a pair of /. Slimes drop mana stars frequently.
 * provides a generic increase to DPS and is a decent filler accessory.

As with most situations in general, it is best to reforge your accessories with damage, critical strike chance or defense increasing modifiers.

Potions

 * ,, , and will greatly increase survivability.
 * Any food item that provides the, Plenty Satisfied, or Exquisitely Stuffed buff is helpful.
 * is a must for mages.
 * will increase mobility.
 * and will improve DPS.
 * ,, or  and  will further improve it for Mages, Rangers, Melee, and Summoner users respectively.

Specific Strategies
During the second stage, Queen Slime follows a fairly predictable pattern. The player can run back and forth on a long platform, jumping over projectiles, and Queen Slime will remain at roughly the same height the entire time, making targeting easier.

Skybridge
Fighting on a long skybridge can make avoiding the spawned slimes much easier. Queen Slime is fairly slow in her first stage, but her winged form can keep up with the mounts summoned by the Goat Skull and Blessed Apple. Be careful if you reverse directions as all previously summoned slimes will still be alive.

Lava Layer
Like nearly all bosses, the Queen Slime is immune to lava, but her minions are not. A thin layer of lava can be used to take out most of her minions. Combined with Lava Waders, Terraspark Boots, Water Walking Potions, or Obsidian Skin Potion, you can easily decimate her. Get a strong single target weapon, like Chain Guillotines or the Sky Fracture and some good armor. Titanium armor is extremely useful as its Titanum Barrier can take out most of the Heavenly Slimes.