Fate Zero had the 1st Cour end after Caster / Gil summoned Cthulhu, then Saber, Lancer, and Rider agreeing to an alliance and Saber remarking I been blessed by the Lady of the Lake and we now see Saber running towards Cthulhu, and we get a very cgi shot of Cthulhu in the water raising a tentacle while Saber jumps up.
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Fate UBW ends with Caster sealing Saber from Shirou and Shirou not being a master anymore. Note the end of the 1st cour / season for UBW is a single episode but it gets a double length just like the Episode 0 and Episode 1 which deal with Rin and Shirou's prologue respectively. Rin tells Shirou stop trying to fight the holy grail war for you are not a master anymore. Then This Illusion plays with Rin and Archer jumping from building to building.
https://www.youtube.com/watch?v=iFZbqUgPgXI
This Illusion and its various remixes (Disillusion) are famous in fate for being the Opening Music for the original Fate Stay Night game. The sound of This Illusion can change very much depending on the instrument used for the melody and whether vocals are added (and there are official versions with both english vocals and japanese vocals) for example in UBW Episode 24 if I recall This Illusion pops up again in instrumental form right before Shirou realizes the truth of UBW and that is the trick and now he can fight gilgamesh toe to toe.
https://www.youtube.com/watch?v=iS9oFjoD9pw