How the Horadric Cube works
The Horadric Cube is found in Act 2 (Halls of the Dead, Dry Hills) and doubles as a portable stash and a crafting bench: drop the ingredients inside, hit Transmute, and the listed result comes out. In D2R every recipe works in all game modes — the old ladder-only restrictions from classic Diablo II are gone, so single-player and non-ladder characters can use everything on this page.
Not all 157 recipes are equally useful. The ones players actually rely on: rune upgrades for cleaning up mid runes, the four socketing recipes (and the Hel unsocket), unique and set item upgrades (exceptional and elite), the Grand Charm reroll (any magic item plus three perfect gems), repair and recharge recipes for charged runewords, crafted amulets and gloves, and the Cow Level and uber portals. Gem upgrades matter mostly to feed the other recipes — perfect gems are crafting fuel.
Recipes worth memorizing
If you only learn a handful: three of the same rune (two from Um up) makes the next rune; three same-tier gems make the next tier; a normal unsocketed weapon or armor plus two runes and a perfect gem rolls sockets; Hel plus a Scroll of Town Portal clears sockets at the cost of whatever is inside; any magic item plus three perfect gems rerolls it — the recipe behind Grand Charm hunting; and Ral or Ort plus a damaged item repairs it without a trip to town.
Crafted (orange) items
The 36 crafted recipes combine a magic item, a perfect gem, a low rune and any jewel into an orange Crafted item — the same base type with preset mods plus random affixes, like a rare with guarantees. The four families: Blood (perfect ruby — life leech and bonus life), Caster (perfect amethyst — mana and mana regeneration), Hit Power (perfect sapphire — a Frost Nova proc) and Safety (perfect emerald — flat damage reduction and resistances). The crafts players actually chase are Caster amulets (guaranteed faster cast), Blood gloves (crushing blow and life leech), Hit Power gloves (knockback, popular on bowazons) and Blood rings.
Crafted output level scales with your character level (ilvl = clvl/2 + ilvl/2, rounded down), so craft on a high-level character for the best affix pool. Elite bases give elite results — a Caster amulet only needs any magic amulet, but a Blood weapon wants an elite axe like a Small Crescent. For the full breakdown — level breakpoints, base shopping and target stats — see our Crafted Items crafting guide.