The Cosmic Cube is an object of vast, almost omipotent power. A cosmic cube is formed when a partcular type of force-field is generated in the shape of a cube (Usually, although other geometric shapes can be used, the shape is realy unimportant.). It was once believed that every 32 years, 4 months, a rift opens in reality that fills the cube with near-limitless energies. This cosmic cube (also called a cosmic containment unit.) can then be used to grant almost any wish or desire. The only thing the cubes, which are semi-sentient, refuse to affect is the realm of the soul (However, if enough willpower is applied, even that taboo can be overcome.).However, as more has been learned about the Cosmic Cubes in recent years, it seems that the waiting period has become known as something of a fallacy, and that a Cosmic Cube can possibly be generated at any time with the right equipment. What's more, it has been revealed that source of the energies used to fill a Cosmic Cube comes from the realm of the Beyonders, a dimension inhabited by entities so powerful and different from anything we know of, that understanding their nature is likely beyond the scope to corporeal beings. However, what is known is that the Beyonders are dedicated to change and advancement, and as such have made the creation of Cosmic Cubes possible so that sentient beings can control and advance their own development.
There have been at least 3 true cosmic cubes created in the recent history of the Marvel Universe, and many more such units were gathered from other realities by the Goddess. One was created by the Skrulls, one by A.I.M. (Advanced Idea Mechanics), and the third was the result of an failed experiment that opened a hole into the realm of the Beyonders. This 3rd failed cube instead bestowed a fraction of its energy upon a man named Owne Reece, who would use the power to become the powerful Molecule Man. The Greater portion of this power coalesced into a being that would eventually come to be known as the Beyonder. However, after a time, all cosmic cubes will eventually evolve into sentient beings. The Skrull cube eventually evolved into the Shaper of Worlds, The A.I.M cube became the creature called Kubik, and after accepting his true destiny, the Beyonder eventually reverted back into a cube which evolved to form Kosmos.
Pretty powerful.