Rune of Bulwark is a earth-elemental master arts introduced in the Trails Universe from Ao no Kiseki.
With a Earth Master Quartz installed, the user calls upon the Earth Sept-Terrion to activate the art. The caster is enclosed within a glowing circle outline being the central core of the magic circle surrounding the entire battlefield.
As the caster remains in place to preserve the circle, all party members gain full physical immunity upon the art's activation. In addition, they recover HP by 20% of the damage dealt per normal attack and craft.