Check for consistency: Why do signs have power here? How does cutting arms relate to the link? The crack as a physical or metaphorical result. Need to establish rules in the world for the magical system.
Conflict: The protagonist wants to break a link that was imposed on them, perhaps to gain freedom or save someone. The Signmaster might be an antagonist trying to stop them, or maybe they are the one who can perform the ritual. signmaster cut arms crack link
Characters: The Signmaster, perhaps a protagonist or antagonist. Maybe a protagonist named Signmaster is trying to break a harmful link by sacrificing their arms. The antagonist could be someone trying to maintain the link. Alternatively, the Signmaster could be a teacher, and a student cuts their arms to break free from a link. Check for consistency: Why do signs have power here