Heartless1190
Author, I think shirou isn't using his potential to it’s fullest. Nasuverse animusphere astromancy can predict future, there was one guy called fluger in elmelloi case files who could use divination with astromancy to predict future (so could luvia) and find the things they desire most, and negate attacks by cutting their future possibility of occurence.Ciel's astromancy spell Calvaria galgalim-star of calvaria (a massive gullitoine of light in the mid sky ) are just few. Animuspheres could use the mana of the outside environment to bolster and stimulate their magecraft. There's even crafting of mystic eyes through spiritual surgery and spiritual evocation. So many possibilities. In DXD their's kankara formula. With near infinite mana he can do all those things. There is no reason his noble phantasm won't work on dxd verse magic system. After all it connects with the very principles of magic namely the the thaumaturgical foundation of a world he is currently residing in. His own own efficiency and skill in using them may vary but his ability to connect with the foundation should have no reason to falter. He should be easily able gain the understanding of the principle Foundation and connect with them with almighty key. Sorry if that came out as a rant. But Honestly it's fraustating to see him not being efficient. However the world where he will thrive will be fairy tail and on a certain extent mahouka. That's my suggestion though. keep the good work up. Don't be disheartened.