It has 2000 when spawned. When damaged, Blue Slimes and Spiked Slimes (Expert Mode only) will break off of it and the King Slime itself progressively shrinks in size. It drops a random piece of the Ninja Set upon death.
The chance of a King Slime appearing in the place of any other slime is 1:300, and holding a Water Candle will improve the spawn chance of King Slime. The King Slime is not immune to lava. Dynamite works very well against the King Slime, but is difficult to mobilize correctly as the King Slime is large and difficult to trap.
A method to quickly spawn a King Slime is to make a brand new (preferably small) map, get to one of the edges of the home biome (about 1/3 away from spawn) and stop in the last place with grass before a new biome begins. Using a Water Candle gives one a 0.48% higher chance of spawning a King Slime.
An equally advisable method is to build a Sky Bridge going to the very end of the world. Plant a Grass Seed and wait for it to cover the dirt, or one may use the Staff of Regrowth to save time and money. Stand at the edge of the world, this will increase the chance of the King Slime spawning as the player is farther from spawn.
An advisable strategy for beginners is to make a small box in the ground with the top open. When the King Slime comes, if the player stays inside the box, King Slime WILL NOT be able to touch the player and the only problem will be the blue slimes, which will easily die to the Muramasa or other swords.
Another tactic is the hit-run tactic, means approach the King slime and get a few good blows and retreat when it is about to jump. While retreating, you could hit it with long-range weapons like the Bow.
An alternate strategy is to make a T shaped tower at least 11 blocks tall, as shown in the gallery. At this height, ground based mobs can't touch the player and even the King Slime can't get itself into the "airlock." However, a weighted weapon or a boomerang may be needed if King Slime is still able to cause damage.
Place two blocks above the player's head with a two block space in between and the King slime cannot reach the player, (however the blue slimes that are knocked off of the King Slime can still reach you). The player can then swing at it from all directions.
The King Slime can't swim, so a good idea would be to make a deep pool (About 5 blocks deep) and make it at least 10 blocks long. The King Slime will be under water, while the blue slimes float up to the surface of the pool. This makes it possible to kill the King Slime while avoiding the blue slimes until the end of the battle. Breathe using a breathing reed, or you can just stay under water if you have enough HP to spare. (King Slime now floats as of 1.0.5)
Note: Most of these methods are not very effective due to the 1.3 patch, thanks to the devs giving him the ability to teleport.
- A glitch is to trap the King Slime in a cell, and then create a barrier around him. Then, take sand, and place it through a single hole in the top of the cell. Once the whole thing is filled (Although probably it shouldn't be needed), he will start to clip through the ground when he jumps.
- It is possible for two or more King Slimes to spawn at the same time.
- King Slime is similar to a lot of other bosses from other games:
- In Ninja Gaiden, one of the first bosses is a giant slimy monster that devours you. If you look closely in the center of the King Slime you'll see there is a ninja trapped inside. Armor that resembles Ryu's is the one that King Slime drops, so it might be a reference to that boss. While the King Slime jumps it seems like the ninja moves along with the slime.
- King Slime was also the name of a boss in the MMORPG Maplestory, which Terraria shares other elements with.
- There is also a rare monster called a "King Slime" in the Dragon Quest Series, although it bears little resemblance to Terraria's.
- This is the largest slime in Terraria.
- The Dryad will not spawn after the defeat of the King Slime, even though it is considered a boss.
- Despite the boss being a slime, it won't drop gel.
- King Slime now drops Royal Gel upon death if on expert mode.
- Will spawn once 150 slimes (75 if King Slime has been defeated before) have been killed during Slime Rain.
- Sprite changed.
- Can now warp to player when stuck.
- King Slime now drops 5 new items.
- King Slime has the same chance of spawn rate even on a Hallowed Desert.
- Can now be spawned using Slime Crown.
- Multiple King Slimes should no longer spawn simultaneously.
- Now floats in liquids and doesn't make a splash sound when hitting water.
- Added to the game.