Add functions as a Mystic Code—an alternate vessel for the Holy Spear Rhongomyniad—crafted to preserve the weapon’s arcane essence. Rooted in Arthurian legend, its power resides within a geometric cube that accompanies Gray, the spear’s chosen wielder. This form obscures Rhongomyniad’s true identity while enabling dynamic combat versatility, shifting seamlessly between configurations like a scythe, bow, or shield to suit tactical demands.

The cube possesses a loquacious demeanor, its speech patterns echoing the brash wit of Sir Kay, brother to Artoria Pendragon. This linguistic imprint implies the Mystic Code’s personality draws from historical or mythic figures tied to the spear’s lineage. Beyond battlefield adaptability, Add enforces strict limits on Gray’s access to Rhongomyniad’s latent energy. Emergency protocols temporarily override these restraints in dire scenarios, permitting her to harness the spear’s full might—though prolonged use risks eroding her physical form and sense of self.

When Gray is categorized as a demi-servant in certain contexts, the Mystic Code merges with her capabilities as a Noble Phantasm. This integration reflects Rhongomyniad’s mythic stature and adheres to frameworks dictating servant summoning and power allocation.

Add’s bond with Gray hinges on equilibrium: it mitigates the spear’s corrosive effects on her body while offering strategic flexibility. Their interplay accentuates the artifact’s duality—both a guardian against annihilation and a conduit for catastrophic force. The cube’s incessant chatter underscores the fragile symbiosis between restraint and release, weaving narrative tension through their shared burden of power.