Ancient debris is one of the most valuable resources in Minecraft, due to it being a source of netherite scraps and thus netherite ingots. It is found in Nether most commonly at Y=15, although mining at higher levels is safer due to lower risk of mining into a lava ocean. While strip mining is still a potential and straightforward way of mining for ancient debris, using explosives is a lucrative possibility due to its high blast resistance. Furthermore, beds are commonly used, as they explode when used in Nether and are cheaper than other explosives.
This video compares the methods to find ancient debris, between strip-mining, the bed method and TNT method.
Using a diamond pickaxe with at least Efficiency II, the player can instantly mine the netherrack. With the proper angle, this makes it possible to mine while maintaining sprint. The player can then go in one direction until they hit lava, and proceed to mine in another direction. However, it is highly recommended to have multiple potions of fire resistance, as it is possible for the player to accidentally run directly into lava. Compared to using beds or TNT, traditional mining is very resource-efficient, as only tools and food are strictly needed. This method allows you to go about 12 blocks, per second.
It is recommended to have Mending and Unbreaking III on the pickaxe. This way, the player can mend their pickaxe by mining the quartz found along the way. This allows for the player to mine for ancient debris for as long as they have food. Also, the player should mark the coordinates of where they started mining so they can easily find their way back.
The Bed Method
This method utilizes the fact that beds, when used in alternate dimensions, explode with a larger blast radius than TNT. It is easy to do, as you don't need to mine a lot. You will, though, use up many beds, requiring reliable wool and wood resources. Furthermore, given the extremely large amount of damage bed explosions deal and the presence of underground lava pools, it may be advisable to bring Totems of Undying, Armor enchanted with Blast Protection and Potions of Fire Resistance to protect yourself.
- Step 1 - Mining
Mine all the way to Y = 15, as there will be the highest concentration of ancient debris in the exposed blocks.
- Step 2 - Crafting
Place a crafting table and craft a good number of beds. If your inventory is full, put unused wool and planks in a barrel or other storage. Don't use chests, any nearby piglins will be angered and will come to attack you.
- Step 3 - Main Tunnel
Start mining a tunnel. At every 16th block, mine 2x2x5 tunnels (2 blocks wide, 2 blocks high and 5 blocks long) perpendicular to your main tunnel.
- Step 4 - Placing Beds
Place a bed in the side tunnel with the head of the bed facing the main tunnel.
- Step 5 - Protection
Place a solid block (you can use the netherrack from mining the tunnels) in front of the head of the bed.
- Step 6 - Explosion
Standing behind the solid block, right-click on the bed. You should take almost no damage. After the explosion, you may find up to 3 Ancient Debris in exposed blocks. Nearby nether gold ore might also break, dropping gold nuggets you can collect, and many more unbroken blocks will most likely be revealed by the blast. You can mine these out if you like, but note that nearby piglins will anger if you mine these blocks.
This video explains the process of exploding beds for ancient debris. It also suggests a second explosion which is not necessary, but can increase the chance of getting ancient debris.
Repeat these steps on the other side and repeat it, until you have no beds (or food).