This isn't precisely a crossover, but it's between two works in the same continuity, so I think its close enough for this thread.
Prior to the start of the Fourth Holy Grail War, Kiritsugu and Irisviel summoned their Servant using Avalon, Excalibur's sheath as a focus. They were hoping for a Saber, King Arthur, the King of Knights. Unfortunately for them, there was/is/would one day be/could one day be another Servant with a link to Avalon. At least he's a Saber though.
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Stand between the Silver Crystal and the Golden Sea.
"Youngsters these days just have no appreciation for the magnificence of the legendary cucumber." --Krityan Elder, Tales of Vesperia.
Prior to the start of the Fourth Holy Grail War, Kiritsugu and Irisviel summoned their Servant using Avalon, Excalibur's sheath as a focus. They were hoping for a Saber, King Arthur, the King of Knights. Unfortunately for them, there was/is/would one day be/could one day be another Servant with a link to Avalon. At least he's a Saber though.
-----
Stand between the Silver Crystal and the Golden Sea.
"Youngsters these days just have no appreciation for the magnificence of the legendary cucumber." --Krityan Elder, Tales of Vesperia.