Skeleton Spawner XP Farm (Bones & Arrows)

A spawner is a fixed block that keeps trying to spawn its mob type in a small radius around itself, as long as a player is nearby and the conditions (mostly darkness and floor space) are met. Your only job with a skeleton spawner is sealing that whole radius off from any outside light, since even a small leak can quietly starve it of valid spawn spots without anything looking wrong.

Encase the spawner's full activation range in solid blocks, usually around a 9x9 room, so it's totally dark no matter what's happening outside. Don't skip corners here. A light leak is the most common reason a sealed spawner farm just underperforms for no obvious reason.

Water gently sweeps spawned skeletons off the floor and down toward the kill point instead of making you fight in a cramped, pitch-black room. Two water sources creating a slow current toward a central drain is enough. Signs or trapdoors at the water's edge block the flow without blocking the mob's fall, which keeps the current exactly where you want it.

At the bottom, leave roughly a one-block gap where you stand to finish off anything that survives the fall (a long enough drop nearly kills them, leaving one hit). Bones and arrows fall into a hopper-fed chest below. Skeletons occasionally spawn holding bows or wearing armor too, so it's worth checking the chest for the odd useful drop.

Bones from this farm are worth automating on their own merits. Bone meal is the fastest way to force-grow crops and saplings at scale, and a skeleton farm running in the background alongside a crop farm means neither one ever needs restocking by hand.