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The newest and perhaps coolest recipe of all for the Horadric Cube was added in the v1.04 patch, and allows you to make new Rares of many types of items. The recipe is 6 perfect skulls with a Rare item, so the Rare has to be 3x2 or smaller, to leave space for the skulls. Therefore no spears of any kind (including Lances), no Gothic bows, no Polearms, etc. Armor and many weapons will fit, and all smaller items such as rings, amulets, gloves, boots, belts, and helms.
This is a potentially great recipe, since the Ilvl from the affixes on the resulting Rare can go up to 100, meaning that any prefix or suffix in the game can result. Prismatic on rings and amulets, +2 on amulets, Kings on weapons, etc. Six perfect skulls can be hard to come by, but the potential for a great item is very strong, and with the Ilvl = 100, you can get stuff you couldn't gamble until Clvl 84, and you can't gamble exceptional items at all. However you might get a really crappy item as well, it's all the luck of the draw.