User:MentalMouse42/Anvil Mechanics



This page explains the mechanics of the anvil. The anvil is used to repair swords, tools, armor, and even bows, combine enchantments on two items, and rename items. All of these functions cost experience levels, and some also have material costs. There are several basic modes of operation:
 * Repairing an item with units of its material (e.g., iron ingots for iron tools or iron armour). This doesn't work for bows.
 * Repairing an item by combining it with an unenchanted example of its kind. This does work for bows.
 * As an extension of the previous, an anvil can combine two enchanted items, producing one with a combination of their enchantments. This, too, works for bows.
 * An anvil can also rename any item, not just the ones it can repair.

Base value of items
The most important concept for using an anvil is the "base value" of an item, figured in experience levels. Almost any change made to an item will cost its base value, plus costs according to the change. An item's base value is the sum of the costs of its enchantments, plus a charge for the number of its enchantments. Note that the item's material does not affect its base cost, nor does the order of its enchantments. An unenchanted item has base value 0.

There will also be an extra cost if the item has previously been altered in an anvil, see below for details. For repairing (including merging) an un-named object, this will be 2 levels per prior repair. However, renaming an object will permanently set this penalty to 2, regardless of later repairs or renames.

As formulas:
 * For each Enchantment, ECost = Cost-per-level&times;level
 * For the item, BaseValue == ECost1 (+ Ecost2 + ...) + NumEnchantCost + PriorPenalty

Finally, an extra value (NumEnchantCost) needs to be added based on how many enchantments the item has, which can be found from the table below.

Notes:
 * 1) Enchantments marked with a (*) are ones for which the enchantment table cannot produce the highest level.  The anvil can, but this will involve the penalty for prior repair.

Example: Say we have a sword with Sharpness 3, Knockback 2 and Looting 2. Referring to the table we see that the Enchantments will cost 3&times;1 &rarr; 3, 2&times;2 &rarr; 4, and 2&times;4 &rarr; 8 respectively, and another 6 levels for having three of them. 3+4+8+6 &rarr; 21. In the anvil for the first time, this sword will cost at least 21 levels to work on, even before considering what to do with it.

Renaming and Prior Work penalty
An anvil can rename any object, but the price goes up (once) after the first time, while the prior-work penalty becomes constant.
 * Renaming a random item (without durability) costs 5 the first time, then stays 9 for all later renames. Naturally, prior-repair penalties and base value do not apply.
 * Stackable items can be renamed as a stack; you do pay for each item, but the total cost is capped at 39 levels, for which you can rename a full stack.
 * Note that renamed items in general will not stack with normal items, and renamed blocks lose their name when placed.
 * Renaming something with durability costs (Base Value)+7+Penalty, after that it's (Base Value)+10+Penalty.
 * For an un-renamed item, the prior-repair penalty is 2 levels for each prior repair or combination an item has been through. If combining two items, you pay both their penalties.
 * For an item which has been renamed, its prior-repair penalty is set to 2, and remains so regardless of later work. It might revert to its full value if the name were somehow stripped from the object, but as of 1.4.4, this does not appear to be possible. (Renaming the item back to e.g. "Iron Sword" doesn't change the costs.)
 * Simultaneously renaming and repairing an object costs both charges, but you only pay for base value and the penalty once. So if repairing an object with base value 5, for the third time, would normally cost 12 levels (5+3+4), but you are also renaming it for the first time, you pay 5+3+4+7&rarr;15.  If you then damage it slightly so that the next repair cost would be 2 levels (over BV+Penalty), the renamed item will cost 5+2+2&rarr;9 levels to repair, or 19 (10 more) if you are also renaming it again.

Unit Repair
This is the process of repairing an item by adding units of its material: leather, wood planks, cobblestone blocks, iron ingots, gold ingots, or diamonds. (This doesn't work for bows, flint-and-steel, shears, fishing rods, nor carrot-on-a-sticks.) Each unit can restore up to 25% of the item's maximum durability, and multiple units can be used at once (incurring only a single prior-use penalty for next time). The cost in levels to do this is the item's base cost (including prior-use penalty), plus a cost for each unit of material.
 * For most materials and all armor, the cost per unit is 1 for each enchantment on the item, plus 1.
 * For diamond tools (including swords), each unit again costs 1 per enchantment, but then 1 to 3 more. For a multi-unit repair, all but the last unit cost 3 apiece.  However, the last or only unit can cost less, depending on how much durability it restores:  Up to 199 durability costs 1 level, 200 to 299 costs 2 levels, and from 300 to 390 (the unit max) costs 3 levels.

Combining Items
The anvil can be used to combine two items of the same type. The first item here is the target item, which will receive any repair or extra enchantments. The second item will be destroyed, it is the sacrifice item.

Sacrifice Repair
If the second item is non-magical, or if its only enchantments are already higher power in the target item, the combination will simply repair the target. This works for anything with durability. You always pay the base cost for the target item, but the additional costs vary by material, and sometimes the durability of the sacrifice item:
 * The resulting durability will be D=floor(T+S+0.12*MaxD), up to the item's maximum. Here, T is the durability of the target item, S is the durability of the sacrifice item, and MaxD is the maximum durability for the item type. That is, the sum of the two item durabilities, plus a bonus of 12% of the maximum durability, rounded down. This means, that to get the most out of repairing, the durability of the target and sacrifice items should not total more than 88% of the total durability of the item, otherwise you will lose some of the 12% bonus.
 * For swords and tools, the bonus comes out to 3 for gold, 7 for wood, 15 for stone, 30 for iron and 187 for diamonds.
 * For any item with a maximum durability below 178, the cost will only be 1 level. Items with higher maximum durability can pay more. The exact amount depends on both their maximum and current durability, up to 17 for repairing with a near-intact diamond sword or tool. The formula is L=floor((S+0.12*MaxD)/100) with a minimum cost of 1, and the results are shown in the table below.
 * You also pay any prior-repair penalties on both items.

Combining Enchantments
If the sacrifice is enchanted, some or all of its enchantments can be merged into the target, with a few special cases. The level cost can be fairly complex, and adding multiple enchantments can add up quickly. Remember that except in Creative mode, there is a limit of 40 levels for all work in an anvil; if it costs more than that, the anvil will refuse the job. In general, putting the more powerfully enchanted item in the first slot will cost less, but repair costs can reverse that, especially for diamond tools. Some groups of enchantments are incompatible; an item can have only one of them no matter what. The incompatible groups of enchantments are:
 * Sharpness, Smite, and Bane of Arthropods
 * Protection, Fire Protection, Blast Protection, and Projectile Protection
 * Fortune and Silk Touch

The cost in levels can be summarized as L=R + A + (Ek...)+Y. To explain this formula:
 * 1) If the target is damaged, R is the repair cost for the target, not including any prior-repair penalties.  (As above, this may depend on the durability of the sacrifice.)  If the target is undamaged, it is simply the base value of the target.
 * 2) A is any prior-repair penalty for the items.  If the item has not been renamed, that will be 2 levels for each time that either target and/or sacrifice has been repaired on an anvil.
 * 3) For each enchantment on the sacrifice, Ek will be one of the following, added into the cost.
 * 4) If the target has the same enchantment at a higher level, the target level will be unchanged, but you pay nothing for it.  (Ek = 0)
 * 5) * If all the sacrifice's enchantments fit this, and the target is also undamaged (that is, nothing to repair), then the anvil will refuse the job altogether.
 * 6) If the enchantment is incompatible with an enchantment on the target (e.g.. Smite over Sharpness), add its level to the cost, but the target is unchanged.
 * 7) If the enchantment is higher level than the target, the target will be raised to that level, costing twice the per-level cost times the gain in level.
 * 8) If the enchantment is equal on both items, but not "maxed out", the target will be raised by one level, costing twice its per-level cost.
 * 9) If the enchantment is at max level on both target and sacrifice, add its per-level cost to the total.   (Naturally, it will not be changed on the target.)
 * 10) Finally, add Y, a charge for adding enchantments:  If any enchantments are being added to the target (not just raised in level), let X be the number of enchantments added, and T the total number of enchantments on the result.  Add Y=X&times;(T-1)+1.  If no enchantments are added, Y=0.

Examples:
 * For the first slot, take the example above, a sword with Sharpness 3, Knockback 2 and Looting 2. Its base value is 21.  Suppose we add on a sword that has Sharpness 3 and Looting 2.  Both sharpness and looting are equal to the target, but not maxed out, so we add twice the increment for each, 2 and 8 respectively.  Thus the cost will be L=21+2+8=31 levels, producing a sword with Sharpness 4, Knockback 2, and Looting 3.  (Its BV is 4+4+12+6 &rarr; 26, but it will also have a 2-level penalty for the next repair or merger.)
 * Consider a sword with Sharpness 3 and Looting 2 (BV 14) in the first slot, and a sword with Bane 2 and Looting 2 (BV 15) in the second slot, both "virgin". The Bane will be blocked by the Sharpness, but cost 2 levels anyway.  The Looting will combine as above, costing 8 levels.  The final sword has Sharpness 3 and Looting 3 (BV 18). You pay 14+8+2&rarr;24 levels.  If the order of the swords are switched (Bane in first slot and Sharpness in second), the final sword would end up having Bane 2 and Looting 3 (BV 19), at a cost of 15+8+3&rarr;26.
 * And a simple one: A Sharpness 4 sword (BV 5) for the target, and a Looting 2 sword for the sacrifice.  Adding the looting costs 4&times;4&rarr;16.   We have one new enchantment, leaving the target with two, so X=1, T=2, and we pay Y=2.  Total cost is 5+16+2&rarr;23 levels, for a sword with Sharpness 4, Looting 2 (BV 4+8+3&rarr;15).
 * Don't do this: Take a helmet with Protection 4, and Respiration 3, and add a helmet with Blast Protection 4 and Respiration 3.  You pay 4 levels for the incompatible Blast Protection, and another 4 for the maxed-out Respiration.  With the base value of 19, you've just paid 27 levels for nothing.  (Okay, you could still be repairing the target, but that costs even more.)

铁砧机制