Also, in the original material, the ritual can be resisted by a roll that includes the affected character's supernatural power stat - for the purposes of this RP let's consider that Magic Resistance and the Mana stat are the revelant quantifiable characteristics that replace it, due to how MR works and how magi course prana through their circuits to resist magecraft. If Angra is mostly a Servant, then she's by definition a spirit/ghost, and susceptible to the ritual, as Servants are specifically "Ghost Liners" as well. And since she has mediocre stats and no magic resistance to speak of, that means her only real option is to attack Lawrence to try and disrupt his focus of the ritual, since she can't resist the ritual enough to simply escape. It doesn't mean it's probable, but it's still giving her a choice, and a chance to fight back and possibly escape if you manage to convince me with some good writing.
You want Cinematic? There you go.