Here's a fun summary of episode 15.
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Shirou decides to carry Saber like a Prince carrying a King....okay, that's probably a wrong analogy. Anyway, he decides to carry Saber so they can run away from Berserker faster. But Shirou ends up feeling tired so they decide to shack up in an abandoned house and have some fun threesome together. Shirou, however, is not used to threesome and he starts hallucinating about getting his arm chewed off by an ugly looking CGI dragon and then meeting Saber inside the creature's stomach. Yes, I think that's more or less what sex feels like. The next morning, Saber and Shirou wake up blushing as if this is their first time being eaten by a dragon.
Moving along, they got caught up by Berserker and Illya so they decide to fight him off. Shirou tries to shoot Berserker with puny arrow. Berserker wants to smash puny human but Illya tells him to get the girls first before Shirou. Berserker, a gentleman as always, agrees that girls should come first. When Saber is in a tight spot, however, Rin jumps forward to throw some exploding jewellery which freezes Berserker's right arm. Unfortunately for her, Berserker's left arm wants to re-enact King Kong with Rin. Rin, not wanting to be outdone, uses more exploding jewellery on Berserker's head. Berserker momentarily stops moving. But Illya explains that Berserker has 12 x life or rather, 7 more left now. With this in mind, Illya orders Berserker to squeeze Rin to puree.