Is there an optimum enchantment strategy in Minecraft?
Many of the various items have a list of enchantments that would be ideal. For instance, I might want Infinity, Power, Flame, and Punch all on a bow... and at the highest levels. Barring incredible luck, I will never get those with an enchantment table.
I can enchant books until I find those spells, and add them to the bow with an anvil. However, at some point (I haven't yet figured out how many times) it will no longer allow you to add enchantments to an item, saying that it's "too expensive". There is a hidden counter that is incremented every time, and once this goes past a threshold you can never add more magic (though, I've read in places you can continue to repair the item at great cost indefinitely... not clear if that's true or not).
This counter is cumulative, such that if you combine two items' magic into a single item, that won't sidestep the limit.
However, I've only just caught on that one can also combine two books. I can take two Power I books, and make a single Power II book. And I can take two of those, and get it up to Power III, and so on, but also have two spells combined in a book.
If I do this until I get all the magic I need onto a single book (or even just two or three books, supposing the books max out), will I get to the point where the books will no longer combine with the item because it's too expensive? Or are books exempt from the cumulative counter thing? It would suck to spend so much time and effort to get a powerful book and discover that it can't actually be used on anything.
Also, is it true that you can indefinitely repair, as long as you have the repair material and are at level 39? Or is that a misunderstanding of the rules (or maybe just an earlier version of the game and it no longer works like that... I'm on 1.8.9)? Does that only work for those items that can be repaired with diamond/iron, or will it work for fishing rods and bows as well?
Solution 1:
The mechanic in question here is the so-called Prior Work penalty.
Enchantable items, including books, have a Prior Work penalty stored in their NBT data (RepairCost). The prior work penalty is added to the base level cost of working the item in the anvil.
For a new item, this cost is 0, and it is independent of the enchantments on the item. Each time you do anything with the item in the anvil, such as repair, combine or rename1, the prior work penalty is doubled, and 1 is added. E.g. it is 1 after 1 working, 3 after 2 workings, 7 after 3, or (generally) 2N – 1 after N workings. After 6 workings, the prior work penalty of that item will be 63, making it impossible to work that item any longer outside of creative mode.
When combining two items, both penalties are added to the cost, but the new item's penalty is calculated using only the higher of the two penalties. The optimal strategy is therefore to start high up and combine items with similar prior work penalties.
For example, you want to get a Power V, Infinity I, Flame I, Punch II bow: From enchanting/loot/villager trading, you have a Power IV bow, and Power IV, Infinity I, Flame I and Punch II as separate books. All 5 items have a penalty of 0.
If you just go and put everything on the bow, the bow will have been worked 4 times. Instead, you start by combining the Bow and 1 Book (1 working), and the 3 other books into one (2 workings), then combine those two. You'll end up with only 3 workings this way. You could even combine the bow with yet another book (or bow) before that and still end up with 3 workings on the final bow.
1 Renaming does not apply prior work penalty in 1.9.