PROJECT 7: HEAVY ON THE MAGICK WITCH FARM
|Project coordinates: X -1789 : Y +19 : Z +1702
Ever since witches appeared in 1.4, there's been a fervour to farm them for their drops. Imagine an unlimited supply of redstone, glowstone, gunpowder, sticks, bottles... and the rather less useful sugar (no, not the canes, annoyingly) and spider eyes. All you need to do is find a witch hut - a 9×7 platform where only witches can spawn - and turn it into an automated farm!
Actually, it's not quite so easy. I found this out when Data first made one in his old Build Big Or Go Home series, and big it was - mainly due to the amount of work needed to make it work properly. Slabbing an area something like 280×280 blocks? It took him six days, if I remember rightly. And then it had to go through several revisions as it kept breaking - there was lots of finnicky redstone in restricted places because he, like just about everyone else involved in complex redstonery, firmly believed that there had to be a 20×20 distance each side of the spawning pad made only of air blocks in order for the spawn rates to be acceptable.
The original shifting floor design, the kind usually associated with JL2579 and his German pals, is one that's banned according to my rules because it relies on the witches glitching through the redstone block floor as it moves. Data's next design was a chequerboard floor with only half the spawning space. And I just couldn't bring myself to believe that this business with the air blocks was true, especially as one design - that of Anthomas101's 60 Minute Minecraft - used enclosed spawning pads to great effect. Because everything's in the dark there, the witches will spawn in the hut, and every so often a timer releases water from dispensers in the corners of the spawning pads, actively washing the witches down a hole where they are splattered to death. Data's design is like the one in a zombie-spawner XP farm - move the zombies away, up a tunnel that forces them to rise, and then drop them from a suitable height.
I made several tests of various designs in a creative test world. Some kept the air blocks and made sure the witches were constrained to their spawning area with glass, others were totally enclosed. Some transported the witches away to a far distance before sending them up a chute then down to their deaths - some just dropped them off the platform.
One of the most annoying things about witch farms is the way the land around them needs to be "conditioned" to eliminate spawning space for any other mobs - hence Data's massive odyssey of slabbing a 280×280 area on the surface. All the caves in that area - actually, a 280×280×63 volume below the surface - need to be brightly lit so that regular mobs don't spawn there in the dark and that is far from trivial. However, help seemed to be at hand in the form of sZPeddy's redstone-free witch farm, where the witches are killed by iron golems. sZPeddy suggests leaving the golems to do their thing while you wait AFK at an area high above ground level - high enough so that nothing can spawn in the caves below the surface, and all the spawns will occur in the witch hut. I thought it was too good to be true... and it was. The witches would eventually kill the golems, and would spawn and spawn and spawn on one of the levels, constantly attacking each other and healing so that none of them ever die. What I wanted to do was drop the witches off the platform but also wait AFK high in the air. The thing is, mobs despawn when you're more than 128 blocks away. sZPeddy's idea was to be about 125 blocks above ground level because the witches don't have to drop downwards... whereas what I needed to do was drop them down about 30-odd blocks. And that meant... if I reduced the height of the AFK pillar, then there'd be 32 levels below ground all with dark caves spawning regular mobs that would in turn ruin the spawn rate of the witches. Gah!
An even worse complication was that Mojang has tweaked the light level code, so that mob spawns in dark areas were only about 40% of what they once were, thus bashing the efficiency of witch farms down to 40% of what they once were. At least respite came in the 1.8.1 update, where all of a sudden the witch spawn height around the hut was increased by two blocks... this meant a three-platform witch farm was now possible rather than just two of the classic design.
My final test was to see how efficient the "enclosed" design would be, if all the spawning space in the 280×280×63 volume was removed... which I did with lengthy use of the new /fill command. Whether or not the air block malarkey does affect the witch spawn rates I no longer cared after running this test. Splat, splat, splatsplatsplatsplatsplat they went, filling a double chest with their various wares in an hour. That should be more than enough. So I knew my tactics. Build three spawning floors, making sure they're at the correct height. Ignore the air block business and shroud the spawning platforms in darkness. Have dispensers filled with water on one wall, which can all be triggered simultaneously with the redstone circuit from Koala's mob farm, so that they're given about 30 seconds to build up, then just enough water flow (5 seconds or so) to wash them all off the platform, straight down a 30-block deep pit to their doom. Unfortunately, this meant my AFK area would have to be underground, and so I'd need to light ALL the caves! Grinding tedium lay ahead. Minecraft isn't always fun, you know.
This farm has been updated: see Project 18: Fixing The Holes.
For the second update: see Project 43: Tweaks in 1.10.
Typical production rate per hour: 894 sticks, 409 bottles, 429 redstone, 437 glowstone, 453 gunpowder,
429 sugar, 416 spider eyes - total 3,466 items
There is one final point to be made. In one of Data's final episodes of Build Big Or Go Home, where he fixed any of his mighty machines that were broken before Minecraft Down Under started, he did not fix his witch farm. By this stage, his once grand design where he had once had a shifting floor (and no more), where he had taken note of leaving the 20-metre radius of air blocks, had broken to the point where it was near-useless. Other mobs were spawning in it where it had been rigorously designed so they didn't, and after 15-20 minutes there would barely be any witches. I was also sure that in another episode before this one, Data had mentioned the spawning rate dropped off suddenly after a while, so I tested the old shifting floor design via one of his world downloads, and found there was a sudden drop in the spawn rate at 50 minutes, with no explanation.
This was a huge concern when I built this witch farm - if I can leave it AFK while I'm in bed (in real life!) overnight, that's a potential 7-8 hours of loot gathering time which I don't want to disturb continuously. So to get the production rates, I set the farm going and recorded what was in it every 10 minutes - even the sugar and spider eyes that I wouldn't usually collect. The spawn rates for all the items do vary, from 50-something to 90-something in each 10-minute chunk, but will all add up to 570 plus or minus 50 and will do so consistently even after two hours, with no noticeable decrease in the overall drop rate. So I concluded this farm is working just fine, and should be until the end of days.