You can find the Underground Hallow in the Cavern layer, which is directly under the surface Hallow. You must be in Hardmode to farm the Rod of Discord, since the Underground Hallow doesn’t appear until after the Wall of Flesh is defeated. It has a drop-rate of 0.2% in Classic mode, and a drop-rate of 0.25% in Expert mode. This tool allows you to teleport anywhere you place your cursor, with the drawback of losing 1/7th of your health each use. Chaos Elementals spawn at a slow rate naturally, so the most efficient way to farm them is by creating an automatic farm. Let’s dive in.
Preparing To Farm
1. The Proper Gear
The Underground Hallow is a dangerous biome, especially to visit immediately after starting Hardmode. You should at least have pre-Hardmode armor like Molten, but early Hardmode armor like Cobalt or Palladium is best. For weapons, anything past pre-Hardmode should be viable. You’ll need a Molten Pickaxe or better to be able to mine everything within.
2. Materials for the Farm
Here’s a glance at what you’ll need for the automatic farm:
Large stack of any block Stack of any wall 300-400 Pearlstone Blocks 10-20 Wood Platforms 1 Bed 1 Trapdoor 1 Lava Bucket Frog Leg Accessory
Farming Chaos Elementals (Auto Farm)
Chaos Elementals have a chance to spawn on only three specific blocks:
Pearlstone Pearlsand Pink Ice Blocks
Given this parameter, it is possible to make a farm that is not inside the Underground Hallow, though you still have to be in the Cavern layer. To begin, you’ll need a large open space, about 200×200 blocks in size (you don’t have to measure yet, just approximate). Tip: You can use explosives to quickly clear it out. Dynamite and Sticky Dynamite are two of the best in the game. Next, you’ll want to create a row of Pearlstone about 200 blocks in length. Now, you’ll want to measure 50 blocks above and 50 blocks below the row of Pearlstone, creating a large box by the end. You can do this by actually creating a box around the area with blocks. Once that’s done, you’ll want to clear everything within, leaving a large open area. Note: You don’t have to create a large box, it just helps with measurement. If you’re confident the space is the correct dimensions, skip this step. The next step is creating the actual farming area. This should be done in the middle of your large Pearlstone platform. Don’t worry about finding the exact center, just approximate. For this, you’ll want to create two staircases and a space in between. There are no exact dimensions to follow. The purpose of the staircases is to trap the enemies, so just use a reasonable height. In the image below, the staircases are 12×12 blocks, and the open space is 12 blocks in length. Now, use the bucket of lava in the space. Enemies will now burn to death when they fall in. The next part of the farm is the room under it. There is where you’ll be standing so enemies will attempt to go to you, but fall in the lava instead. There are no specific dimensions for the room, but the interior must be at least 7 blocks in height. On the floor, place the chair and table. Use the trapdoor for the entrance, not wooden platforms. The next step is creating a wooden platform under the lava for you to stand on and draw enemies towards you. This is where the Frog Leg accessory comes in. Chaos Elementals stop spawning when you have not moved in 5 seconds. Frog Legs allow you to simply hold down the jump button to keep jumping, bypassing the movement parameter. Note: Break the background wall in the area where the platform is. Chaos Elementals will stop spawning if you are in front of a wall. The final step is the bed. You will die to Hallowed Mimics and Enchanted Swords since they can go through blocks. By placing the bed and setting your respawn point under the farm, you can immediately return to the platform by holding the jump button.
Advanced Tips
If the Skeleton Merchant is present, the spawn rate of Chaos Elementals will be reduced, meaning you’ll have to kill it whenever it appears. This is also the case with Hallowed Mimics. An easy way to avoid this problem is using dart traps. Place three on both sides of the farm. What you want to do next is actuate them. This can be done by placing actuators on them, linking each side to a switch using wire, and then turning the switch. If done correctly, you should be able to walk through them. Go ahead and remove the actuators and wire now. To enable the traps, you need a timer. A 1 Second Timer or any time lower than that works fine. Simply link the traps to a timer, and they should fire at a consistent interval. With this, Skeleton Merchants are killed, and Hallowed Mimics are activated. The Hallowed Mimics will phase through the blocks and kill you, but they’ll despawn immediately afterward, and the Frog Legs will allow you to quickly reposition yourself.
