Does Syrena Kill Philip?

Syrena kissed Philip, confirming the legend that a mermaid's kiss prevents drowning by giving him the ability to breathe underwater, and pulls him into the pool. Philip was taken by Syrena as they swim through the pools to freedom. His further fate is unknown.

What did Serena do Philip?

She told him to not let her tear go to waste. She then went to find the injured Philip and he asked for her forgiveness. Bringing him underwater, Syrena kissed Philip to heal him and gave him the ability to breathe underwater.

Does the mermaid kill the priest in Pirates 4?

While the debris fell, a mermaid saved Philip by pulling him out of the way. When he got up, he found the mermaid and stabbed her in the tail fin as he believed he was being attacked, an act he later regretted deeply.