What if at the end of Kiritsugu's grail war (the 4th?), the explosion was a result of an expulsion of the corrupted essence in the grail. From what I know, a different caster would possibly be summoned for an immediate change. There's also a possibility of the fallout of the corruption affecting Shirou in some unforseen way. Whether anyone is able to tell that the grail is no longer corrupted could also be left up in the air.
Or has something similiar already been done? Thoughts?
Or has something similiar already been done? Thoughts?