Shield Stones are used to protect the caster from an opponents attack. The caster must choose wisely how many shield stones to use in a battle. The more shield energy used, the less powerful you will be in attack.
Wizards of Yan do not always have to use shield stones. Sometimes he or she will be able to say a spell such as "Sum, Yan, Altas" then their shields are more stronger and enhanced because of their powers. Regular RaDosians cannot summon stones from their bare These shield stones do a lot more and if someone has shield breakers (i.e.: Malco), the shield stones would be useless against those sigil power stones.
When he died in the war against the Ethos, he was brought back by Nazmul. His shields, which he had carried in the rocks on his armor, became permanently attached to his body, giving his body the defensive strength of ten shield stones.
He also does not lose his offensive power in both physical and magical while his shields are bonded. This is because his shields are now a part of him.
Vanguard Aegis Edit
Summons a shield that can withstand attacks. Requires any amount of shield stones, but attacks get weaker depending on cost. Can also stack or multiple users can form in a way to offer protection on all fronts (e.g. Ogama Defense formation in "The Road Less Traveled")
Summons a shield dome or group of shields that surround the caster, covers attacks from all angles, but not as effective in some cases.
Summons mini-shields of the sigil used. These shields can block small attacks, pick up smaller objects, deflect some spells or attack an enemy (Snare used this function against Adam). These shields are controlled by the caster.
Much like Vanguard Aegis, but more fortified and joins with other Defenders.
The only shield that attacks. It uses Barricade Array functionality, except can enclose an enemy and possibly disintegrate it, more potent against energy forms. Requires at least 2 Defenders to use.
Much like Fortified Front. It was used in the Episode "Vitus" and Melosa used it to defend Seth and herself against an old guardian guarding something near. It has two stones which will be able to last for some time, depending on how many shield stones you use.