King Slime

Info
King Slime is generally accepted as the easiest boss in Terraria. He is Pre Hardmode, and has the appearance of a giant blue slime with a jewel-encrusted crown on top. Inside of him, there is what seems to be a ninja, frozen in space by the king's obviously hard gelatinous structure. When you kill him, you will get one of three pieces of Ninja Armour, which is evidence the ninja inside of King Slime is not alive.

King Slime will attack the player by trying to land on top of them with his huge bounds. He will also spawn multiple Blue Slimes and Spiked Slimes to help him. On Mobile, PC and console versions of Terraria, King Slime can teleport to the player if they manage to get too far away from him.

In order to summon King Slime, you must use the 'Slime Crown'. Crafted at a Demon or Crimson Altar with 20 gel (99 gel on 3DS versions) and a gold/platinum crown. King slime may also be summoned by killing 150 (75 if King slime has already been defeated prior) slimes during a slime rain, or he may randomly spawn on the outskirts of the map for no reason.

Strategies

 * If possible, always have a nearby house with a nurse and a dryad living there. The nurse can completely refill your health for a few silver coins, and the Dryad generates the 'Dryad's Blessing' buff which increases your defence. She also generates the Dryad's Bane debuff that negatively effects enemies.
 * Have ranged weapons for King Slime, as he uses melee attacks primarily, staying at a range and firing at him would ensure you take minimal damage. But beware, if you move too far away from King Slime, and you are playing on Mobile, PC or Console versions, then he may teleport directly on top of you.
 * King Slime is not immune to the On Fire! debuff, and therefore using flaming arrows or other fire-related weapons against him is recommended.
 * If you are not a fan of ranged weapons, then use a big sword. When he jumps at you, move the opposite way while swinging your sword. If done correctly, you should have hit King Slime as he jumped over you and dealt damage. Repeat this method until King Slime is defeated, being aware of the slimes he has spawned and his very big jumps.
 * Make a long, flat arena, with heart lanterns, Campfires and Fireflies/Stars In Bottles. For additional help, make vantage points with wooden platforms to shoot at King Slime. Beware King Slime can choose whether he would like to stand or fall through a wooden platform, and you will not trap him.
 * If you have already killed King Slime in Expert Mode, then equipping the Royal Gel he drops inside of his treasure bag will grant you immunity to the slimes he spawns but not him.

Achievements and Usefulness

 * By killing King Slime you earn the 'Slippery Shinobi' Achievement (pictured below)




 * King Slime has a 25% chance of dropping an item called the Slimy Saddle, which summons a ridable slime mount. This mount is useful in both Skeletron and The Eye of Cthulhu's boss fights, as it allows you to jump on the bosses while taking no damage as a consequence.
 * King Slime has a 33.3% chance to drop a 'slime hook' which can prove as a very useful grappling hook, and an alternative to trying for ages to find the Goblin Tinkerer.
 * King Slime drops 1 gold, which (if you have not already) is enough to house the Merchant