How the Horadric Cube planner works out its odds

Where do the Add, Remove and Reroll odds come from?

From the game data, not from measured cube results. Each line's weight comes from the game files as Maxroll's planner exports them (build 3.2.1.73552). An Add picks among the prism's lines that can roll on your item, by weight. Remove and Focused Reroll pick the line that goes evenly among the lines they can take, as players report. We assume Chaotic Reroll picks evenly too; that is our reading, not a report.

Nobody publishes measured cube rates. Player reports of 50 to 150 Protector's adds for All Resistance fit these weights: All Resistance weighs 33 in a Protector's pool of 929 to 1,229 on an empty item, so it lands about once in 28 to 37 adds, and 50 to 150 adds is bad luck at those odds.

Weapon Damage counts as one line with one weight, 400. The game data lists a copy of it for each weapon type; we read the game as having one Weapon Damage line. This is our reading, not a measured rate.

Are the enchant odds measured?

No, they are our estimate. No source publishes how the Occultist picks its two offers. The planner assumes they are drawn by the same affix weights, two different lines from those that could roll on the item, so a heavy line such as Maximum Life is offered far more often than All Resistance. Each enchant try costs 10 Forgotten Souls on an Ancestral item, and the gold cost rises with every try.

How does family blocking work?

A line on the item blocks the other lines of its family from Add and Reroll results. Maxroll's cube guide gives the plain case: an item with Maximum Life can't get another. The families come from the game data. Examples:

• The six single resistances are one family: Fire Resistance blocks Cold, Lightning, Physical, Poison and Shadow Resistance. All Resistance is in no family, so a single resistance does not block it.
• Damage is one family with Fire, Cold, Lightning, Physical, Poison, Shadow and Holy Damage: Damage blocks each of them that can roll on your item.
• Critical Strike Damage and Damage over Time are one family, so Critical Strike Damage blocks Damage over Time.

That is why one Chromatic Add on an item with Fire Resistance can only give All Resistance.

Why does a full item need a Remove before an Add?

An item holds at most 4 lines, and Add Affix needs a free one. So on a 4-line item a Remove comes first. Remove Affix does not work on Legendary items (items with an aspect); there the planner uses Focused Reroll, Chaotic Reroll and the enchant.

How does the planner use Chaotic Reroll?

Chaotic Reroll costs 1 Refined and 15 Raw dust plus the prism, and works on Magic, Rare and Legendary items (Maxroll's cube guide). The prism picks which kind of line goes. What the new line can be is not published: Maxroll's guide says it is of another category.

The planner assumes the new line can be any line that can roll on the item, of any kind, the prism's own included, drawn by the same weights as Add, and never a line already on the item or of a family on it. Its odds on the page are this estimate. It matters most on Legendary items, where Remove does not work.

What does Must keep do?

Unless you tick Must keep, a plan may take any line, wanted or Greater, and rebuild it, when that is the cheapest way to finish the item. A step that can take a line you want says which, with its odds; a step that can take a Greater Affix says so on its box, with the step that puts the line back. The text version of the plan also says what finishing costs from there. A Greater Affix that goes comes back as a plain line: players report that the cube never makes a Greater Affix.

Tick Must keep on a line and no step will risk it. When that makes the plan dearer or rules it out, the page says so and gives the cost without it.

An enchanted line, even one kept with No Change, is never picked by Remove, Focused or Chaotic Reroll. Maxroll's crafting guide says so for rerolls without a prism. That it holds with a prism too rests on one test by the site's owner, and the planner counts on it. So a plan can also lock a line you don't want, do the cube work around it, and enchant that same line into a line you want at the end.

What do the Luck row and the 9 in 10 figures mean?

The expected cost is the average over many crafts. The Luck row gives the spread of prisms over a whole craft, worked out exactly from the same odds. For example, “Half of crafts use 11 prisms or fewer; 1 in 10 uses 30 prisms or more” means half of players finish within 11 prisms and 1 player in 10 needs 30 or more.

On a step you repeat, “9 in 10 players are done within 4” means 9 of 10 players get the result within 4 tries. When a repeated step can also end on a result that changes the plan, the page gives the chance a line you want lands in the step, and the 9 in 10 of those landings.

The game gave something the page says can't happen. What now?

Choose “Something else happened” at the end of the list under step 1, then enter the item's lines as they are now. The roll and its cost are logged, Undo puts the old lines back, and the plan works out the rest from the lines you entered. A result the page calls impossible means one of the rules above is wrong for your item.