These abilities allow him to join together or split apart practically anything. From fusing a chainsaw and a crossbow to create a crossbow that fires chainsaws, to breaking down spaghetti into its basic ingredients, there really isn't much of a limit to this particular ability.
Unity Dream is a tall humanoid alien clad in silver and bronze armor. He has what appears to be large toasters mounted on his shoulders and small turbines on his arms. He has boot-like feet with high heels, and his midsection has the appearance of a large yellow star. The symbol of an unknown Omnitrix is on his torso.
The fusions and/or fissions Unity Dream creates, while technically stable, are not exactly guaranteed to produce good results.