Guides & Cheat Sheets / Anvil & Enchantment Mechanics
Anvil & Enchantment Mechanics
Why a combine that worked fine three steps ago suddenly says "Too Expensive" — and the order that keeps it from happening.
The prior-work penalty
Every time an item goes through an anvil — repaired, enchanted, combined, even renamed — it remembers how many times that's happened. Each use adds to a hidden iSometimes called the "anvil tax." It isn't shown anywhere in the UI — the only sign it exists is costs climbing faster than you'd expect. prior-work penalty that makes every future anvil use on that item cost more levels, on top of whatever the enchantments themselves cost.
The penalty doubles (and adds one) with each use, so it compounds fast:
| Times used in an anvil | Penalty added to cost |
|---|---|
| 0 (brand new item) | +0 levels |
| 1 | +1 level |
| 2 | +3 levels |
| 3 | +7 levels |
| 4 | +15 levels |
| 5 | +31 levels |
In formula terms, the penalty after c prior uses is 2^c − 1. When you
combine two items, the resulting item inherits whichever of the two penalties is
higher, plus one — not the sum of both. That one detail is the entire reason the
combine order below works.
The 39-level "Too Expensive" cap
The total cost of one anvil operation adds together the prior-work penalties of both items, the enchantment levels being added, and a flat cost for repairing durability or renaming if either applies. In Survival or Adventure mode, if that total ever comes out above 39 levels, the anvil refuses the operation outright and shows "Too Expensive!" — it doesn't matter how much XP you actually have banked, the interface won't let the combine happen at all.
This is almost always a prior-work problem, not an enchantment-cost problem: two items that
have each been combined four or five times before will hit the cap even with cheap
enchantments, simply because 15 or 31 gets added twice before the
enchantments are even considered.
The binary combine order (how to actually avoid it)
Since combining takes the higher of two penalties and adds one, the losing strategy is applying books to your final tool one at a time — the tool's own penalty climbs by one on every single application, so by the fifth book you're paying the level-5 penalty (+31) on top of everything before it.
The fix is a merge-tree: combine books together in pairs first, and only touch the final tool once, right at the end.
One-at-a-time (expensive)
Tool (0) + Book A → Tool (penalty 1) + Book B → Tool (penalty 2) + Book C → Tool (penalty 3) + Book D → Tool (penalty 4). By the last book, you're paying the level-4 penalty (+15) just to attach it, on a tool that's now been through the anvil four times.
Binary pairing (cheap)
Book A (0) + Book B (0) → merged book (penalty 1). Book C (0) + Book D (0) → merged book (penalty 1). Then: Tool (0) + merged-book-1 (penalty 1) → Tool (penalty 2). The tool only ever goes through the anvil twice, and the highest penalty anywhere in the whole tree is 1 — not 4.
The general rule: keep every branch of the tree as balanced as possible, and always merge two items with equal (or close) penalties together rather than feeding a high-penalty item more low-penalty ones one at a time. This is exactly the order the Anvil Enchantment Optimizer works out for you automatically.