The Key of Terror, the Key of Destruction and the Key of Hate must be placed in the Horadric Cube while standing on Harrogath to open a portal to the Forgotten Sands, Furnace of Pain and Matron's Den.
This can be (ab)used to create Rune Word armor with extremely high defense: for example, a Prudence body armor's (140-170)% Enhanced Defense would result in (2,628-3,645) defense when made in the socketed ethereal Sacred Armor. Since Rune Words can have variable bonuses, in the event of an unfavorable roll the Horadric Cube can also be used to El + Eth + Perfect Ruby + Normal Set Weapon = Exceptional Set Weapon. Eld + Ith + Perfect Topaz + Normal Set Armour = Exceptional Set Armour. Dol + Mal + Perfect Ruby + Exceptional Set Weapon = Elite Set Weapon. Hel + Io + Perfect Topaz + Exceptional Set Armour = Elite Set Armour. The following Horadric Cube recipes have been changed or added