King Slime

The Slime Crown works anywhere in the world at any hour, with no biome requirement and no progression check, which is why he is the one boss you can pick a fight with the moment you finish crafting. He also turns up on his own. In daylight there is a small rolling chance for him to spawn out near the far left or far right edge of the map, on ordinary green grass above ground, in dry conditions, and not while you are in a graveyard. Once that check passes he materializes somewhere near you rather than on the block that qualified. He is one of only two bosses that can still ambush you like that in a world where he has already died.

During a Slime Rain, killing enough ordinary slimes brings him out to close the event, and statue spawned ones count toward the tally. If you have beaten him in that world before, the number needed is cut roughly in half. This runs the other way too. If a rain has started and you want nothing to do with it, summoning him with a crown and killing him ends the event exactly as the natural finish would, which is the quickest exit from a rain you did not ask for. Dying to him instead only makes him leave, and the rain grinds on for another half day of game time. Remix worlds replace all of this with a small chance on each slime death, but only until the first time he falls and only once somebody in the world has enough health and defense to be worth his attention.

He chases by hopping and the hops run on a loop: two ordinary jumps, one short one, then one that goes far higher than the previous three prepared you for. That tall jump is what lands on people who have settled into a rhythm on a flat arena. As his health falls he physically shrinks and the pause between hops shortens, so the fight speeds up while the target gets smaller.

You cannot hide from him and you cannot cheese him with height. Put solid blocks between you, or get roughly ten tiles above or below him, and a five second countdown starts. When it runs out he appears next to you, and from far enough away he lands directly on top of you whether or not you are in midair. The timer pauses when you break the condition but it does not reset, so ducking behind cover repeatedly just spends the same countdown in pieces. The tell is clear enough: he shrinks in place and his marker on the map slides toward the ground, which is how you know he is coming back while he is still off screen. Every teleport restarts the jump loop from the beginning, and because of his size he sometimes reappears half inside terrain and sits there stuck until the next one.

Damage makes him bleed blue slimes. He drops a small handful the first time you dent him and again each time you take another chunk out of his health, so a fight of steady medium hits produces far more of them than one where you erase a third of his bar in a single shot. In Expert some arrive as Spiked Slimes instead, and those are the actual danger in the fight for most players. He throws one last batch out when he dies, and that group is always plain. Piercing weapons are the answer here, because a spear or an arrow that punches through a slime and still lands on him means you are never choosing between clearing adds and making progress. The adds pay you back too, dropping hearts and mana stars, and unlike him they drop Gel.

Those slimes are ordinary spawns underneath, so they can roll into the rare variants and they can carry whatever the current event has added to the drop pool. Summoning him inside a prepared farm rather than out in a field is a real strategy: it is one of the faster ways to fish for biome keys, pirate maps, holiday drops and the yoyos that come off common enemies. It also produces gel in bulk, which matters if you are feeding a flamethrower or making asphalt.

The first kill pops a Nerdy Slime out of his body, a town pet that stays with you afterwards. The Angler opens up two new fish requests, the Demolitionist adds Freeze Bombs to his night stock, and if Queen Slime has also fallen the Princess starts selling Royal Romance. None of that locks him out. The crown resummons him as often as you like, and he keeps randomly spawning as well.

He is one of only two bosses lava will actually hurt, which tells you roughly how the game rates him. For the Worthy doubles his size in both directions and speeds his jumps up considerably, turning the easiest boss in the game into something that crosses an arena in two hops. The figure trapped inside him is where the Ninja gear comes from, and his trophy is a slimed over ninja blade to match. And despite the reputation, he hits harder than almost every other pre-Hardmode boss, which is not what most people remember about him.