In this guide, I’ll be covering the Brain of Cthulhu, a boss who isn’t too difficult on lower difficulties but can be insanely hard on Master Mode.
He’s definitely not as hard as the Eater of Worlds, but he still can be somewhat difficult if you don’t have the right gear. What’s great about the Brain of Cthulhu fight is that you don’t need to make any arena at all.
Unlike the eater of worlds fight, the Brain of Cthulhu doesn’t have any special attacks when you fight him above ground, and you don’t even need to prepare much at all.
The first thing you need to do is get the best gear you can at this point. I’m assuming you haven’t beaten Skeletron yet, so the best armor you can get now is either Platinum or Gold armor.
Once you have the armor, my favorite weapon to use against the Brain is the Tendon Bow along with Jester’s Arrows. The reason you use these arrows is because they have an amazing piercing ability that can help destroy the Creepers that follow him around.
For accessories, you’ll want the best movement accessories you can find. I’ll be using Terrapark Boots and a Blizzard in a bottle, along with a Shield of Cthulhu. The Shield of Cthulhu is important because it’ll help you avoid damage in the second phase of the fight.
Now to make this easier, you can place some campfires and heart lanterns all around the area you’ll be fighting. I think it’s easy enough that you don’t need an arena, but if you have any trouble at all then make a quick arena using wooden platforms.
When you have everything set up, summon the Brain of Cthulhu with a Bloody Spine, and wait for him to come to you. The first phase is super easy to deal with using the bow, just keep shooting at the Creepers and dodging. You’ll also want to watch out for normal enemies, but they aren’t too hard to deal with.
The second phase is where things start to get harder. The Brain of Cthulhu will teleport right next to you, and you’ll need to shoot him before he touches you. I like to dash with the Shield of Cthulhu in any direction, and even if you dash toward him you won’t get damaged.
Just keep shooting him with the bow and dashing until he’s defeated, and the Brain of Cthulhu will drop the Treasure Bag and Master Mode relic.