Ben returns to the place where he found the mysterious Omnitrix. In the rubble, he discovers a previously missed "key" that fits into the body of the watch and kicks his alien heroes up to the next level with Omni-Kix Armor!
If you think Diamondhead is tough, check him out in his Armor! When hit by a blast of energy, he just flexes his mighty Omni-Kix Gauntlets. Not only do they shield him, they absorb the energy and fire it right back!