Guide:King Slime strategies

"The lord of all things slimy."

The King Slime is a boss in pre-Hardmode.

Spawn Conditions
King Slime can be spawned when any of these occur:
 * Naturally on Grass beyond the Dungeon and Jungle (this is approximate: it might be farther or nearer depending on world size);
 * Naturally by Natural-occuring Slime Rain;
 * Using.

Battle
King Slime is no different than a normal Slime: it moves by hopping to the player. Unlike slimes however, it has a large pool of health due to its status of boss, and it's huge. This makes King Slime an easy target, but don't let that deceive you: its jumps are very far and unpredictable (it's height also vary, depending on the distance between him and the player), and failing to predict it's jump destination can make you get damaged.

Getting too far to King Slime will make him teleport to you, meaning that you can't escape by just running out of screen. You can use it to your advantage however, as it can get stuck in enclosed spaces.

As King Slime gets damaged, it gets smaller. While this makes him harder to get hit, it also makes him more mobile, having less issues to escape small enclosures (should it fail however it might teleport instead), and it spawns lesser to harass you. These can make you waste ammo on them instead of the King Slime, so the use of piercing weapons or ammo is important.

Killing King Slime only makes your life in Pre-Hardmode easier: its drop can greatly help you move around, but doesn't help you progress in the game. It makes the Slime Rain to stop however.

The main difference between these versions with is that it doesn't teleport: it can get eternally stuck in small enclosures if it spawns there, but it's mostly the same.

Expert Mode
There are not many changes about the King Slime itself besides its higher Damage and Health. However, when damaged it will spawn in addition to regular Blue Slimes. Those can throw volleys of spikes at a short distance, so having a weapon which can pierce multiple targets and attack from a range will be necessary to avoid being bombarded to death.

Terrain Preparation
Due to the fact this boss can't pass through blocks, there are some arena options:
 * The player can add traps to this pit, which would make the fight even easier or:
 * A flat area with small room below it with Platforms as roof for the player. King Slime can't enter small rooms and thus can't touch the players in this room.
 * An arena made up of platforms and Ropes for both horizontal and vertical movement would help.

It is also recommended to close any caves near the summoning spot, since the boss might spawn inside and get stuck.
 * Make a small 2*4 pit cover the top with wooden platforms and shoot upwards.

Another strategy is to make something that will help you later, a long minecart rail path. If you go high enough, he will not be able to teleport or jump on you. His attacks relies for you to be on the ground. To the AI it seems that you are on the ground, so he just stands under you and occasionally jumps, making him an easy target.

Armor
Iron armor/Lead armor or higher is recommended to reduce the damage of Blue Slimes summoned by it to an insignificant amount. However, this boss isn't hard without armor, if using a good arena.

Weapons
Most weapons can be used to fight this boss without difficulties, except Shortswords. Piercing weapons may be preferred, to hit both the blue slimes and the king slime himself.

However, melee users may have trouble fighting the boss due to the knockback immunity, unlike ranged users which can stay in an unreachable place without getting hit. Recommendations:
 * Gold/Platinum Broadsword or better.
 * Lead/Iron Bow or better with piercing arrows such as Unholy Arrow or Jester's Arrow.
 * Any kind of Guns, Spears, or Flails.
 * Vilethorn, this weapon hits through blocks and pierces infinitely until the duration ends and therefore very good for fighting King Slime.
 * Crimson Rod, if using a small enough pit, the king slime will stay in one spot and this weapon can do a lot of damage.
 * Any weapon that can go in one direction, such as a Gem Staff.
 * The Artery works well with the string and counterweight accessories, because of the good range and the DPS it can deal.
 * Using Grenades can deal a lot of damage to the King Slime. The only issue would be dodging your own grenades, as they can deal damage to you as well even if you're the one who threw it.
 * Molotov cocktails will deal tons of damage to the King slime and the blue slimes spawned by it due to its area of effect and the on fire debuff towards them.

Accessories
Like weapons, most accessories can help:
 * Shackle can help reduce the damage of the boss and his minions.
 * Hermes Boots, Flurry Boots, or Panic Necklace can help avoiding damage or running away in bad situations.
 * Cloud in a Bottle, Blizzard in a Bottle, Sandstorm in a bottle, and/or Rocket Boots can also help with vertical movements.
 * If you have defeated the Eye of Cthulhu in Expert Mode, the Shield of Cthulhu can be useful both in damaging the King Slime and minions, and making a quick escape.
 * A Band of Regeneration can be useful to increase rate of regeneration while avoiding being damaged by King Slime

Potions

 * Ironskin Potion can help reducing the damage received even further.
 * Regeneration Potion
 * Any food that grants Well Fed buff.
 * Swiftness potion, so you can evade the teleports and run under the jumps if needed.

No teleports Strategy

 * Build a one-block thick wall 18-20 blocks high;
 * Create a walkway between 35-50 blocks long with platforms for maneuverability;
 * Make sure a is nearby.
 * Use any long-range weapons (Yo-yos, Bows, Gemstaves or Throwing weapons).

Rope Strategy
An easy way to defeat King Slime is to do this: This way, you are practically invincible from him, as he cannot jump to you, and there is no surface for him to teleport on.
 * Make a rope around 20-30 blocks high from the ground
 * Use any weapon that has range (bows, staves, shurikens, grenades etc.)
 * Climb up to the rope, and shoot King Slime.

Lava pit Strategy
Because the King Slime can be harmed by Lava, a good strategy is to use a to make a long strip of land with a small amount of lava (shallow enough so items don't burn) and then make some widely placed platforms. You can jump, use rocket boots, or use a grapling hook to move between platforms. Just be careful to not jump in the lava if you don't plan to use. This strategy works with his teleports, and the minions will all die from falling in the lava. You don't have to focus on fighting, because the lava will dish out major damage. You can also skip the platforms, and use a Obsidian Skin Potion, and just evade by running under the slime, or using the Boots to fly over.