Coordination - Walking On Narrow Surface

Over the course of their adventures, a character might end up walking up on a small beam, narrow ledge, or even a rope. To avoid falling and move forward, the character has to make a Coordination check.
Walking on a narrow surface does not exclusively mean that the character is standing up. If the situation allows it, a character can walk on all fours, using their hands to stabilize themself.
Is is possible to engage in combat while on a narrow surface. Yet, balancing while fighting is a challenging task. When doing so, the character upgrades the difficulty of all checks they make while having to keep their balance. In addition, enemies add b to their combat checks when attacking the character. Finally, enemies can spend aaa on their check to force the character to immediately make a Coordination check with the normal difficulty for the situation. Should they fail, they then lose their balance and fall.
For characters less skilled in keeping their balance, it is possible to suspend themselves from a rope or beam using both their hands and feet and pulling themselves along the rope. This kind of movement requires more strength than balance and thus uses the Athletics skill. The suggested difficulty for such checks is Average (d d). You can still use the Walking on Narrow Surface tables for modifiers and symbol usage.
The difficulty of the check is based on how wide the narrow surface is.
EXAMPLE #1 OF A WALKING ON A NARROW SURFACE CHECK
Buck is a young arcanist who is attempting to flee a campus for the Collegiante Arcane after faking his death. Seeing his way out blocked by two men, Buck decides to go through one of the guest rooms, which is currently vacant, and tries to reach the exit by moving along the campus's exterior walls. Buck looks by the windows and is relieved to see that there is a little ridge he can step on. He gets out and start walking toward the main gatehouse to escape. 
The ridge he's using is as wide as his feet. Therefore, the GM is calling for a Hard (ddd) Coordination check. Since Buck can use the campus' masonry wall to stabilize himself, the GM adds b to the pool. The roll generates fhh. The GM spends the hh to have Buck drop an item. As the arcanist slowly progresses on the ridge, his sword's scabbard clings to a nail coming out of a wooden beam, preventing him from progressing further. As he attempts to dislodge it, he slips. While he was able to avoid falling down, the leather strap holding the scabbard to his belt was torn apart. The sword falls on the grass two stories below. Buck sighs as he finds himself in a position where he will not be able to defend himself without magic should he get caught.
Since the check was a failure, he did not progress far enough to reach the king's window. Buck must make another roll, using the same modifiers. This time, it generates sht. Since he succeeded, the arcanist will get to the window. The GM spends the h to have a guard patrolling around the castle to notice the sword on the ground and start looking around. Buck's player spends the t to have the arcanist slip back through the window just before the guard can see him on the edge. This way, the whole castle will not be alerted. Yet, the guards will still be on alert and getting to the gatehouse might prove trickier than expected.
EXAMPLE #2 OF A WALKING ON A NARROW SURFACE CHECK
Kylus is an assassin tasked with murdering a constable who has recently been sabotaging Kylus' organization's plans. The assassin knows that the constable usually goes to a specific tavern at the end of the day. Unfortunately, the target is never alone so Kylus has to plan how to achieve his mission. He goes to the tavern prior to the constable's arrival and looks for a way to poison his target without being seen. He notices that wooden beams stretch across the room above the tables and there is enough space for him to walk upon them. These are accessible from the staircase leading to the rooms on the second floor.
He gets a table and waits. Once her target is seated and the tavern gets busy, he leaves her position, goes up the stairs and steps on the wooden beam. Now he has to walk unnoticed until he gets above his target.
The wooden beams are as wide as his foot's length. The GM calls for an Easy (b) Coordination check. The roll generates ssht. Kylus walks up the beam and gets right above his target. He takes out a vial of poison and manages to pour a few drops into the constable's mug right before he takes a sip. The GM spends the h so that when he is putting the vial back in his pocket, it slips, falls on the table and shatters. As the constable is already struggling with the ingested toxin, the alarmed guards look up and see Kylus. Kylus's player spends the t to have a suspended chandelier just beside the table. Kylus cuts the rope, making it fall right beside the guards and then jumps on the ground. The chandelier hitting the floor buys him time to exit the tavern through a window on the secon floor before the guards can pursue him.