Canon!Assassin loses one life to make it appear that Kirei has betrayed Tokiomi and had been summarily kicked out of the Grail War. Here Tokiomi and Kirei try the same thing... Only for Lupin!Assassin to steal some of Archer's Noble Phantasms and sell them for money!
A flashback reveals Lupin stole Robin Hood's bow for an 'old man Blackmore'. Lupin III collaborated with one of the Dead Apostle Ancestors and stole a priceless historical artifact for him, and both the Church and the Mages Association failed to kill him for that.
The same flashback shows how Kiritsugu and Lupin first met. Natalia and Kiritsugu had been hired to kill the Edelfelt head, and were about to shoot when they noticed that Lupin, who had been hired by the Edelfelt to recover CortÚs' sword, had sneaked up on them with Jigen, and the two thieves were holding them at gunpoint. To add a touch of irony, Kiritsugu was criticizing Lupin's opponents in his mind, commenting they had failed due to Zenigata being held back by being a cop and the villains being too impractical.
Then the situation degenerates in a fight, as Lupin has decided that letting the Edelfelt's head die on his watch would be bad for his reputation... And Kiritsugu was completely outclassed by both Lupin and Zenigata. And that was before Goemon cut down the Golden Gate Bridge to stop the police cruisers and Kiritsugu's bike. And in the meantime, Jigen defeated Natalia in a gun duel.
Caster's death. Including Assassin using a portable flamethrower whose design he stole from a fake mage (Pycal, a Lupin III character) to torch Prelati's Spellbook for added Irony.
Fourteenth Heist: Assassin tricks Kayneth to unwittingly kill his Servant in a hopeless battle, saves Sakura, and also tricks Zouken by stalling long enough for the police to arrive at his house. To top it off, he manages another crazy escape from Zenigata.
Fifteenth Heist: Assassin's "The Reason You Suck" Speech to Zouken. Also, Kirei kills, no MASSACRES Zouken, from those hellspawn Crest Worms he calls familiars to that dried-up, withered little thing he calls a soul and Risei heals Sakura and grants her sanctuary. Hallelujah.
Not to mention Kirei's beatdown of Zouken is punctuated by his own incantation, and the last line Zouken hears before that pathetic excuse for a soul of his leaves this plane?