minecraft-java-edition
I'm playing through an adventure map and I found a large dark cavern I must traverse, but there are just too many mobs (I'm not kidding, there's an insane amount of mobs). I ended up having to wall myself into a corner.
Ordinarily I would wait until morning and walk through it/light it up then, but no sunlight ever reaches it.
What's the safest way to light up a cavern?
You should try setting up an obsidian farm! It requires at least one bucket, but will go faster the more buckets you have. Consider the following picture:
Surround a 1x7 trough with some safe blocks. It doesn't matter what it's made of, as long as the blocks won't burn away (so avoid wood, cloth, etc). This is the object outlined in green below.
Now you should have a 1x7 depression -- you want to put lava blocks into this. Be careful when emptying your lavabuckets, because if you try to place a lava source block on top of another lava source block you'll empty your bucket, losing the lava. I didn't have lava accessible, so for the picture I used cloth. It is outlined in Red.
After you've got your seven lava blocks, simply place a water block on the rim of trough, indicated by the light blue outlined wood block in the picture. The water will flow over each of the seven lava blocks, turning them into obsidian.
This is known colloquially as "obsidian farming".
I saw an interesting design somewhere where the player made an enclosed pen using fences, and put stairs around the edges so the animals could be pushed up the stairs and into the pen, but couldn't escape.
You could also use a system of water canals to try to bring sheep farther away closer, making the task of pushing them into the pen less cumbersome.
Best Answer
Bit by bit, if necessary block by block. I'm not kidding, that's how I'm taking dungeons.