Some flaws...

[nireth]

Amabel quite possibly could have been a Tuurngait and Clarence made you hallucinate that she was a real person after you killed her.

Story-wise however that would make very little sense I think. Amabel was supposed to tell Philip how to get rid of the virus and obviously Clarance wouldn't exactly approve of that.

Now if Amabel really had been a Tuurngait, I can imagine Philip feeling let down and his trust in her being conveniently shaken, that is him wondering if the cure was really a cure and not something that'd make him give in to the virus completely.

As much as Clarance loves his little japes I doubt he'd give up that kind of insecurity and doubt in Philip's mind just for another one.

As it was, finding out that Clarance had deceived him (whether it was true or not) made Philip all the more angry and all the more determined to get rid of Clarance as fast as possible.

Maybe it's personal, but assuming Clarence ignored all that is much harder for me to believe than picturing a worried (and absent-mindedly not minding the ceiling) Amabel walking steadily towards Philip and trying to calm him down while he's acting weirdly, all for the sake of gameplay.