Magma Cube Spawner XP Farm

Magma cube spawners live in the treasure room of bastion remnants, and unlike almost every other hostile mob, light level does nothing to stop them. Sealing a normal spawner room from light, the thing that works for zombies and skeletons, has no effect here. The spawner keeps producing magma cubes in full brightness just as happily as in the dark, which trips up a lot of first attempts.

Like slimes, magma cubes split into smaller versions when hit instead of dying outright until they're small enough. A kill mechanism either needs enough total damage per pass to clear a cube through all its splits at once (a long enough fall, or a hard enough hit), or it relies on multiple passes through a tight kill zone before drops get collected.

There's no usable open water in the Nether, so funneling uses the same solid-mechanics toolkit as a blaze farm: pistons, trapdoors, soul sand bubble columns. The chamber generally needs to be taller and roomier too, since magma cubes, especially the larger unsplit ones, take up more space than a zombie or skeleton would.

Some designs bring in iron golems as the actual kill mechanism, since a golem's melee hit is strong enough to split and finish a magma cube in fewer hits than most player weapons, letting the farm run with less direct involvement from you.

Magma cream, normally crafted from a slimeball and blaze powder, drops directly here as a mob item instead, which is the shortcut ingredient for Fire Resistance potions without needing a slime farm running alongside it. Since Fire Resistance is useful for both the ghast and blaze farms on this page, this is one of the few farms whose output actually makes building the others safer.