Queen Slime

Queen Slime is an early-Hardmode Hallow-themed Boss and is the Hardmode counterpart to King Slime. Her appearance is that of a massive, transparent pink slime wearing a tiara with what resembles an enlarged, more crystallized version of the Gelatin Crystal, which is the item used to summon her, inside herself.

Fighting Queen Slime is completely optional and not required for game progression, but her defeat may reward the player with useful items.

Her Bestiary entry states:

Spawning
The Queen Slime can be spawned by using a Gelatin Crystal. This can only be done in the Hallow. Otherwise, nothing will happen and the item will not be consumed.

The Gelatin Crystal can be found in the Underground Hallow alongside Crystal Shards, and they spawn in the same way as Crystal Shards. Therefore, the Gelatin Crystal needs to be mined before use. Once used, the item is consumed, and the boss is summoned.

Behavior
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, dealing high damage.
 * Will stay in one place for a few seconds, before firing 6 crystal projectiles that break upon impact with a tile. Sometimes, she will perform this attack multiple times in a row.

When at 50% health, Queen Slime will grow wings and begin to fly like a Slimer. Her AI also changes:
 * Instead of firing crystals from herself in 6 directions, she will periodically launch these projectiles towards the player.
 * She will occasionally fire bouncing crystal balls in 8 directions.
 * She will occasionally attempt to fly above and drop down onto the player.

Tips

 * Queen Slime herself has a relatively simple attack pattern with easy-to-dodge attacks. The biggest threat comes from the minions she spawns, which can fill the screen with projectiles and quickly overwhelm the player. Killing or avoiding these should be top priority.
 * While the boss needs to be summoned in The Hallow, the fight can take place anywhere. This means you can go into a different biome once the fight starts and the fight will continue as normal.
 * In Master mode, The Black Spot mount allows you to hover over all attacks in the first phase. It also goes faster than Queen Slime in phase two. Be careful as this can despawn the boss.
 * It is highly recommended to fight Queen Slime in daylight, as at night her attacks may be hard to see.
 * Setting up a basic arena with platforms will make dodging attacks and defeating her much easier.
 * It is recommended to use Heart Lanterns and Campfires to increase Health regeneration rate by providing the Heart Lamp and Cozy Fire buffs respectively.
 * Sunflowers can also be useful, as they reduce enemy spawn rates by providing the Happy! buff.
 * Remember to use the Sharpening Station, Ammo Box, Crystal Ball, and Bewitching Table prior to the battle.
 * Use of the Fetid Baghnakhs together with the Sharpening Station can kill her in a matter of seconds.
 * If you have defeated at least one of the Mechanical bosses, it is recommended to search the Underground Jungle for Life Fruit to increase your maximum health.
 * Make use of banners to reduce the threat of other monsters during the battle.
 * Using the black spot mount and a coin gun with gold or platinum coins can kill queen slime extremely fast even in master mode

Trivia

 * Queen Slime’s AI was created entirely by developer Grox the Great, while the visual effect was created by Yoraiz0r.
 * The Queen Slime is one of 5 bosses with exclusive music, the others being the Empress of Light, Plantera, Duke Fishron, and Moon Lord.
 * The feather covered in slime on her trophy resembles the sword covered in slime on the King Slime's trophy.
 * Queen Slime was one of the two bosses added in the first version of the final major update, 1.4.0.1, along with the Empress of Light.
 * Most of Queen Slime's drops are upgraded versions of King Slime's drops.
 * Mechanically, this boss bears a striking resemblance to The Dark Emperor from the tModLoader mod Tremor Remastered..