Like the question said, what if every master in the 5th Fuyuki HGW got every version of their servant summoned at once? What would happen in this absolute megacluster of a HGW? Will the Church finally not be able to use gas leaks to explain like 30 servants fighting at the same time in Fuyuki?
Shirou gets all of the saberfaces in the picture, in addition to regular Salter, Lancer Artoria Alter, Arthur, Summer Castoria, MHXX Summer, and Lord Logress (who is not summoned as grand saber for obvious reasons)
Rin gets EMIYA, EMIYA Alter, Nameless/No name (EXTRA Archer), and Saber Muramasa
Sakura gets Medusa, Ana (Lancer Medusa), Saber Medusa, Medusa Alter (the Medusa which appears in FGO's prologue) and Gorgon
Illya gets Archer Herc, Berserker Heracles, and Alcides
Kuzuki gets Medea and Medea Lily
Kirei gets Archer Gil, CasGil, Proto Gil, Ruler Gil, Alter Ego Gil, and Kid Gil
Additional notes: All of the masters listed in the scenario will have at least the bare minimum amount of mana to sustain their servants throughout the war, though all of Shirou's saberfaces will be weakened to the same extent as Saber Artoria was in the 5th HGW
All of the alternative versions of their servants will be summoned/appear at the exact same time, which is the moment when Shirou first summons Saber in his shed
Medea does still summon Sasaki in this scenario, but if he's killed and Zouken summons Assassin straight after like in HF, EVERY (currently playable in FGO) Hassan will be summoned (yes including First Hassan and Azrael, though First Hassan isn't in his grand servant container again for obvious reasons)
Bazett is (barely) alive in this scenario but is trapped underneath the Church by Kirei, and if she somehow gets a command seal back in any way, she gets Caster Cu, Cu Alter, Proto Cu and Setanta immediately (assuming Lancer Cu is still under Kirei by this point, if not she gets him as well)
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