Saber knew that the heart of the Illyasviel of their world was the vessel of the Holy Grail, but she did neither understand fully what it implied nor she thought this Illyasviel was the same. If there were no Servants, only these partly summoned 'cards', the Holy Grail was not fully functional for an appropriate summon. At least that had been her hypothesis. Nonetheless, even if she declined her assistance, she would not be only a burden she had to withstand.

"You will provide me prana through a spiritual path once we establish our contract," she told her. She was not the best person to explain the role of a Master. That was Rin’s specialty and she would rather not bother her right now. "I apologize if my answers were vague and unsatisfying. Perhaps you could employ the Caster card briefly to understand better what we must do."

The card would surely provide her with the spell and the natural inclination to forge a contract with Saber as her new Master. At least, from what she discerned how naturally skilled she had been with Lancer’s spear despite of her lack of training.