A written word of power Milk scrawls onto her own skin, burning her but blocking Bianca's fire.
Facing Bianca's incoming spell inside her own guild, Milk cries "Wait," scribbles a power word onto her skin, and holds up her wrist as the wave of heat washes over her. She cries out as the power word burns into her mottled skin, but is otherwise unharmed. Miriam later remarks that she is quite glad Milk cast that spell or whatever she did to protect herself, before treating the burn with a Magical Salve.
The technique fits Milk's trade as guildmaster of the Calligraphy Guild — writing itself is her magic — and it falls inside the self-defense exception permitted to a Non-Combatant NPC.
A glyph written directly on skin that scorches itself into the flesh as it activates.
The calligraphic self-defense that saves Milk's life without breaking her NPC restrictions.