Preparation for the fight starts on day one.
Be alert. Be aware. Be prepared to die, as the world is full of enemies. You are on your own out here. Trees are a terrible foe, and will bring an end to your run if you are insane enough to be doing this on hardcore difficulty.


(Undoctored image)


If you have read ahead on the Terraria Wiki, you will know that the Guide is an elite mobster and hitman, who will attempt to assassinate you should you grow close to him. Be sure to do away with him as quickly as possible.




By the end of day one, your house should look something like this:



This is a sign that you are ready to move on to the next step.

By day two, you may start to notice the appearance of new NPCs. The merchant, for example.



Looks innocent enough, right? Well, you are correct. But you are also wrong. The merchant is not in fact a merchant. He is, in reality, an escaped serial bicycle theif. Don't believe it? I didn't either, until I read this completely real article on the Terraria Forums:
'he stole me bike m8'
-dannydan204
As such, he cannot be trusted. You know what to do.



Soon, as more NPCs arrive, you will begin to realise that none can be trusted - not even the jovial painter. As such, you will be forced to upgrade your holding facilities into something more permanent. You can build an entirely new complex, or you can simply convert your old housing.


They do not need light.
There are no exits. There is no food.
No-one goes in. No-one goes out.
There is no escape.
Make sure you leave surplus room for new arrivals. We wouldn't want the newcomers running astray, would we?

Your good work up to this point may, sadly, yet come undone.
Whilst many strive for good in this world, there are those who believe that creating unlicensed prison complexes is bad. These individuals, coined 'The Police', would like nothing more than to foil your attempt to beat the yellow slime. They also probably have some questions about your taxes which you don't want them to ask.
As such, you must prepare accordingly. You must take precautions to ensure that your complex is not identified for what it is.



It is also a good idea to move all financial arrangements offshore, and to have an escape route avaliable. Do not hire bodyguards, however. They can not be trusted. No-one can be trusted. Only trust yourself, and the voices in your head.

Your final battle with the Yellow Slime is growing slowly closer. Yet, you have far to come. The battle will be a terrible one. And, whilst you are now protected against attacks from behind, you must now look forwards, towards the grandest foe. Those familiar with Lovecraftian lore will be aware that Yellow Slime forms an integral part of the pantheon of Elder Gods. As such, you will have to acquire the help of another Elder God to have a chance. Cthulhu is your best option. To get his attention, follow the following pictional instructions:

1)



2)



3)



4)


With that done, you now have Cthulhu on your side. Yet, you are still not ready. If you have even a modicum of common sense, you will know that the true bane of Yellow Slime is the lobster men. If you followed step 3.14 correctly, you will have turned the oven back down to 500 degrees rankine. This will appease the lobster men, and bring them forth from their watery domain.
At this point, the leader of the lobster men will challenge you to a match of Just Dance 2012. If you possess a dance mat, it is advised that you take this option, as the only alternative is to fight.



If you choose to fight him, then all I can wish you is good luck.

Simply steal the left pedal, and reconstruct the rest of the bike around it. This is far easier than other methods, and is less likely to attract the attention of the constabulary. It is also far more-

...Wait, what?
Yellow Slime?
...
Oh, yeah.
That.

Having gained the favour of Cthulhu and installed yourself as the new leader of the Lobster Men, you are now ready to face Yellow Slime. Be aware that only professional-level Terraria players may even hope to beat Yellow Slime on the first attempt. However, you must beat the slime within three days of your challenge, to stop the moon from crashing in to the planet.



If you followed step 7 correctly, then you should have obtained the Terra Blade at the end of the second night. However, do not attempt to use this weapon on Yellow Slime, as the beast will absorb the weapon's power, becoming unstoppable.


(Artist's impression of the havoc wrought by a fully-powered Yellow Slime)

Yet, you are a skilled player of Terraria. After hundreds of hours, after being oppressed by our yellow slimey overlords for so many years, you can do this. You are the protagonist here, and if fiction has taught us anything, it's that nothing can kill-







It wasn't even yellow.
...
Why me?

Since the release of this guide, several questions have been raised regarding the Yellow Slime. I shall do my best to answer them here.

Question: Can't I just use the last prism, meowmere, etc?
Answer: You can try. Possible side effects include inability to digest gluten, and aching knees. Not recommended on days Monday through Thursday.

Question: What if the Yellow Slime wasn't even the most powerful one? What then? Is the world going to end? Are we all going to die?
Answer: It really depends on whether your oven is working properly.

Question: Can't I just use cheats to beat it?
Answer:


Question: How do you summon the Yellow Slime?
Answer: You do not summon Yellow Slime. Yellow Slime summons you.

Question: SOSIG
Answer: That is not a question.

Additionally, since the release of this guide, I have been made aware of the presence of another, similar guide, aptly titled 'How to Defeat Green Slime'.
https://steamproxy.com/sharedfiles/filedetails/?id=691605782
To clarify, I did not write this guide, nor even know of its existence until this one was effectively completed, and awaiting approval by the High Tribunal of Inevitable Judgement. Whilst it, and its Blue Slime oriented sequel, are generally invaluable, it is not recommended that you use the steps contained within for an encounter with Yellow Slime. Despite the common misconception, Green Slime and Yellow Slime are very different beasts, especially given Yellow's recent interest in smooth jazz.

Furthermore, I have also released an additional informational brochure regarding the survival of Terraria's fourth night, for people who have a ludicrous death wish and cannot be reasoned with:
https://steamproxy.com/sharedfiles/filedetails/?id=1969983821