Hold it. The only reason Saber's instincts lets her dodge an attack that Warps Causality would be against Lancer and Assassin. Even still, Gae Bolg was dodged only because she was lucky. She didn't dodge it, she just had a high enough luck stat. Any subsequent use would have killed her unless she's in Avalon.
Against Assassin, she already bent his sword once. That's the only thing that allowed her to win.