A question about an event in the game [spoilers]

[Kedjane]

Clarence is being able to control all of Philip's senses, but only to a certain degree.
Philip was well-ready and expecting to encounter a infected at any time - thus Clarence had an easier time creating the illusion of her being a monster. Seeing the monster made Philip believe it could kill him, making it easier for Clarence to give Philip the illusion of pain - so strongly that it killed him.
In reality I think Amabel came in and saw Philip, looked at him and saw him going nuts - just stood still and clamly walked towards him asking what was wrong, in fact not moving very much and failing to see what Philip was doing - WHAM! Perhaps she even just walked into the room and stood still in the middle of the room watching as Philip ran around the room like a madman.