Minecraft – How to repair anvils

I have invented a solution to this problem using a mechanism to apply one tick of lava damage. It occurred to me that a tripwire could be placed immediately above lava in order to remove it (using a dispenser) as soon as a mob hits it, thus preventing the mob from continuing to swim in it. Doing this for the water as well as the lava means that no acceleration is needed to make sure the mob will fall down, so the whole mechanism is only a little bit of extra height above a standard fall-damage trap.

Build details, from top to bottom:

• The zombies are pushed by water into the drop pipe. I don't know how important the length of the upper section is.

• The water and lava mechanisms are identical:

  • Each dispenser contains an empty bucket.

  • All pistons are sticky.

  • The tripwire above the fluid is the input to the left (in first image) piston monostable (rising edge detector), which causes the dispenser to remove the fluid into the bucket. The monostable ensures that the tripwire input will not interfere with the second fluid-restoring pulse.

  • Behind the dispenser is a comparator followed by 2 blocks of redstone wire; this detects the dispenser having a lava bucket (which counts as 1 stack) instead of an empty bucket (which counts as 1⁄16 stack), and triggers the right piston monostable to remove the fluid. In the event that the state of the dispenser gets reversed, this circuit will simply not generate a pulse, thus correcting the problem.

• Below the water block is exactly 19 ½ blocks of empty space (counting the sign) down to the fall-damage landing platform.

Results: When the zombies hit the platform, a few still take 2 punches, but most of them take 1 punch to kill. I have successfully operated this mechanism in my survival world fed by two zombie spawners.

Glitches:

• The amount of damage done is not completely reliable.

• It is possible for the dispensers to get inverted (resulting in zombies falling on fire, without taking any lava damage, or from the wrong height). This latest revision with comparators can self-correct this problem, but it still may result in an occasional zombie with the wrong amount of health. (I have also seen a dispenser completely fail to respond to pulses, so I suspect there is a Minecraft bug involved.)

I know it can be hard to build mechanisms from screenshots, so if you would like any further explanation of other camera angles, feel free to ask me to add them.

You can enchant books instead, which always puts only a single enchantment on it, and then use the book in the anvil to apply it to a tool or weapon. You do have to go through a lot of books to get exactly the enchantments you're looking for, and it costs extra to transfer the enchant from the book to the tool on the anvil, but what you get for the loss of efficiency is precision in having exactly the enchants you want.

Note that you can also combine enchanted books of the exact same level on the anvil to get one book that has that enchantment level +1. So, you can take two Efficienty III books, combine them, and get one Efficiency IV book as the result. In this way you can slowly gather together the pieces for your ideal set of magic tools and, with enough XP lying around to go through this XP-inefficient process, get a set of tools to your precise specs.