Title: (C82) [SKUG (BUSHI)] Saber ni Chinko ga Haeru Hon | Saber Grew a Dick (Fate/Zero)
JPN Title: (C82) [SKUG (BUSHI)] セイバーにち●こが生える本 (Fate/zero)
This lingered in editorial limbo for a long time but it’s finally translated. The premise Saber grows a dick and fucks all the guys in Fate/Zero in the ass. Fate as it was meant to be.
You can view it here