An armor that is usually invisible, Cassandra Sandsmark obtained while on a dig with her mother in Cambodia, near Angkor Wat, and is the first to wear it in over three thousand years. It manifests as a red suit with a hood, gauntlets, and a crimson lariat composed of some sort of energy. The war bracelets seem to manifest when she is in danger whether she summons them or not. Her armor also becomes more visible or grows as first demonstrated in the fight with Superboy. It is later revealed that she has trouble controlling the armor and that she sometimes blacks out while using its powers. According to an out of control Wonder Girl, the armor was forged in the sun and that it is looking for somebody strong enough to bear the burden of being a guardian. The wearer needs the willpower to control the armor and keep it silent, which seems to be how it was named.
Recently, Diesel, Cassandra's ex and the first person to unearth the armor, has returned, seemingly from the dead, and stole the armor from her.
Red Robin, Superboy, and Cassandra headed to the collapsed temple, the first of whom recognized the Mark of Trigon carved upon the stones though it is unclear precisely how the armor is related to him.
The Silent Armor is later revealed to have been created millennia ago on either an Earth in a dark and forgotten age or in another dimension in direct response to Trigon's rampage. A brave warrior, Alazandria, donned the suit when Trigon approached her village and managed to stalemate the monster. Unlike any other obstacle, Trigon could not harm the wearer, who in turn did not have the skill to truly over come him. Trigon swore revenge on the wearer, claiming he would one day return with an army of his children, each more powerful than the wearer. So far the only one that has met this measure, is the youngest; Raven.
Since the encounter, the armor passed from mother to daughter until it the armor was either sent away and sealed with in a tomb for unknown reasons, where Diesel and Cassandra would eventually find it.
The armor provides Wonder Girl with the ability of flight, super strength, durability, and the lariat. The lariat is indestructible and can drain the life essence of others. However, Omen reveals that it is also draining Cassandra's life force.
The Armor is semi-sentient and will try to take over it's wearer, if weak-willed, sending them on a rampage. The degree of the Armor's control is visually displayed as more and more of it grows onto it's host. Normally Cassandra can make it invisible, but make it appear in the shape of a pair of ornate bracelets and a piece of shoulder armor. If the Armor gains control of her however, it will grow a breastplate, armored boots and a helmet.
The Silent Armor was created specifically to counter the demon Trigon through blessings by higher magics, making the wearer able to stop a monster that has consumed galaxies. However, this purpose is very specific, and has seemingly failed when Trigon beat and invaded Cassandra's mind with little effort. Likewise, Raven has also managed to ambush and wipe out parts of Cassandra's memory. Also, the Armor appears to be able to tell when Trigon is near and that Raven was of his blood.