Ok, here is a sample master app for Duck mod's master OC, as asked. We highly recommend you give this and the Rules section a read before applying, it’ll really help. App under the cut.
Full name: Mushia Kunitsu
Basic bio: The Kunitsu family is is a well known mage family with little influence or greatness, having traded their pure lineage for sheer numbers of children due to demand from the other mage families because of the Kunitsu's usefulness to them as skilled terrain manipulators and craftsmen. Having slaved away in the shadows of the Tokiomis and Matous to prefect the leylines in Fuyuki and other cities, they had lost all respect as fellow mages. When Mushia Kunitsu, the eldest daughter of the central family displayed a quality of magic circuits far beyond the standard for her many brothers and sisters, she was specially groomed for fight in the holy grail war at Fuyuki and retake her families lost honor.
(Not much to say here. Just a few sentences will do. I think I did too much for this. A lot of it was repeated in the extended bio.)
Extended bio: The Kunitsu family of mages have had a long history of using their mystic code in the service of other greater families. The size of the Kunitsu's family is much larger then most, so the quality of their magic crests have greatly degraded over time. It has been more critical for them to have branches across the world to maintain leylines then to have a smaller family with purer mage blood. Mushia was the eldest daughter of the current family head, born in Indonesia where their family was centered. She displayed a quality of magic circuits that was close to that of a standard mage, which was much higher level then those of others in her family. She would be capable of real magecraft, and as the elders predicted, an expert in the use of the leyline spikes. They were certain that she would be the family's first chance to participate in the grail wars, and their best chance at success.
The Kunitsus held a long grudge with the other magus families of Fuyuki, as the carefully established leylines in Fuyuki were manipulated crudely and without the Kunitsus knowledge to form the holy grail system. Mushia was tasked with capturing the grail, restoring her family to greatness, and then reestablishing the older Fuyuki leylines. Mushia had little contact with the rest of her family, treated like a princess and given all the privacy she liked to study the magecraft that her family had long been incapable of using. But Mushia showed little interest in that form of magic.
The results of her years of reading alone led her to believe that the magic of her own family was stronger then anything the other families were capable of. Forgoing the basic magecraft she had promised to study, she became an expert in the use of her family's powerful mystic code, weponizing it as none had done before her. Finally, she declared that she can learned the ultimate technique of the leyline spikes, one that had been unknown even to her elders. Ready to demonstrate her knowledge in a true war of mages, Mushia traveled to Fuyuki by boat as soon as her command seal appeared. She is 20 by the times she arrives in Fuyuki to fight for the grail, and with just her personal belongings, she lodged up with a smaller branch of her family in a traditional home close to the west Fuyuki beach.
(I wrote in a new family who I gave a slight connection to established Fate families, but still separate enough to have their own history and legacy. Remember that it's ok to make your own mage family lore, and other masters will be informed of it before the game so they can act like had already heard of the family.)
Personalty: From the time she was chosen to one day participate in the war for the grail, Mushia has studied nothing but the art of war. Mostly unguided by her elders however, who were always busy, she was left to her own devices, yet at the same time, she was to show strict discipline and a drive for victory. He strategies are steeped in tradition, and Mushia has built her way of life around this as well. She sticks to what works and follows tradition as a guideline. Her demeanor is nothing more the stone cold to those she does not respect, though she often has little to say, preferring to point out passages from scrolls and books to bring her point across. As she would say, it is wiser to listen to the words of the past then those of the future. She dismisses those who toss away old wisdom as hasty fools, and though she is not opposed to allying herself with another mage, it would only be with those of less skill.
She sees servants as tools to be used, like their personalities are just their complex controls that must be tinkered with to direct them in the proper manner. After providing her flawlessly logical battle strategy, she is sure no servant could come up with anything better. Mushia prefers to wait for her enemies while strengthening her position and draining their mana, so she will try to put a leash on any servant who is overly aggressive. Her wish for the grail is the one her elders passed down to her, that she should wish for the Kunitsu family to be restored to power. If Mushia was allowed to make her own wish, it would be to become the ruler of the world so that she could have absolute dominion over the earth. Though she trusts and respects her family, years of self study have left her believing that she is more capable of leading then any of them will ever be.
Magic: Mushia has been trained in most basic magecraft, yet excels at none of it. The only subject she could be said to having shown any promise in is the crafting of bounded fields, as wards or stabilizers. Her fields can protect or seal the fields of others, creating complex layered boundaries to improve their effects. She can also create fields that serve as wards, giving her vision of an area. The downside is that these fields are all easy to detect by stepping into them, but hard to dismantle for those without intricate knowledge of the land. All of Mushia's magecraft is centered around taking control of the land. Of course, even with the highest quality circuits in her families history, she is still nothing more then an average mage at most. The true power that allows her such territory control is her family’s mystic code, not her direct magecraft.
(the generalization of 'basic magecraft' is ok, but I also listed her specialties and some examples. It was easier because bounded fields already exist in the Fate universe. New forms of magic would require a lot more explanation.)
(My master is a mage so I didn't need to do this section)
Physical description/picture: Mushia wears the traditional dress of her family, a long sleeves, and flowing stripes silver and green on a white fabric, similar to a shrine maiden, yet distinctly different due to it's earthen colors and looser folds. It's good for storing her mystic codes, but not suited for rushed physical activity. Because of this, people often mistake her as a strange cosplayer, but to any half knowledgeable mage, her dress is instantly recognizable as that which belongs to the Kunitsu family. When not in her traditional wear, Mushia has a simple tan fleece sweater that amply covers her neck and arms, complimented by a short brown plat skirt and white leggings. She's about 5'2, a bit on the heavy side, an consequence of her lack of exercise. She is of Indonesian decent, still half Japanese from the Kunitsu side. Her oak wood color hair is done up in a bow when she wears her family dress, but let completely free and down in her face otherwise.
(Could have done this section a lot better. It would have been more then enough with a picture, but sadly I couldn't get one in time. A little more then this would have been nice if I'm not going to use images.)
RP sample: (Not goes to do this cause it's just a sample. Two paragraphs minimum. This is just to see what your responses in threads will be like.)
Skills: Mushia enjoys the study of East Asian history and has a secret passion for boardgames, especially those with eastern themes or gameplay. She devotes most of her time to reading though, and while she enjoys reading alongside others (especially those who make good headrests) she has little desire for small talk when it is not about history. Shopping for books, clothes, or antiques is also something that can bring a smile to her face. In fact she is open minded of most activities, provides that her servant carry her though all waking portions.
(Just a small short section. Hobbies, and miscellaneous non-magical talents go here.)
Mystic Code: The mystic code of the Kunitsu family are the leyline spikes. They are stone spikes, twice as large as standard railway pins, carved from solid pieces of rock. Each spike looks the same, differing only with small carvings and inscriptions. Mushia starts with 20 spikes in her possession and can craft one a day with suitable qualities of stone and the right tools. The language carved on them is impossible to decipher for those without the Kunitsu training or blood. The spikes are used as leyline manipulators, and by striking them into the ground, they can be used to change the natural flow of mana in the terrain. That is only their most basic usage though, and by combining multiple spikes, it is possible to achieve different effects, all though changing the flow of mana in the environment. The spikes can also be removed or activated from afar by a single command from Mushia, Planting spikes in a line along a layline and then activating them at once can cause the leyline to burst and become unusable, releasing huge amounts of concentrated energy in the form of a localized earthquake, and if enough are used in the line, about ten, a deadly fracture could occur, sundering the earth. A triangle shape can be used to redirect a leyline, robbing an area of it's natural mana production. A square shape blocks the mana in a leyline and causes it to build up in that area, which can be useful for quickly harvesting prana. They can be placed in a pentagon leave an area on a leyline void of mana over time. There are other uses with other shapes, but the ultimate technique requires ten, to form a pentagram star, and then activating the center spike causes all mana and prana in the inter pentagon to be instantly drained and then absorbed into Mushia. It is the perfect anti-magecraft tool, robing any mage of their prana and ability to produce it until they leave the area. If it catches more then one mage though, the absorbed prana could overload Mushia and kill her, unless she had a suitable vessel to transfer it too. The weakness of the leyline spikes is their lack of direct combat application and time required to set up. Still, they make fighting Mushia on the area of her choice an impossible task.
(Now this is a A rank mystic code. It has to be if their entire family is based on it. I used the established concept of leylines and expanded on them in a natural way for the Fate universe. It's clearly an A rank mystic code because of it's versatility and potential for creating deadly traps. But it has weakness too, and lacks direct combat application. Notice how I tried to give as many examples of it's use as possible to leave very little to the imagination.)