Whoa! How can someone tell me this episode is a bad one with the whole scenes that we saw?
The off-screen work was the best of this episode. Still we see the cave with water set! And they really used it here... Besides of incredible scenes under water and in the exterior. When the episode starts we can see Phoebe swimming under sea, only for that I am able to say that this episode is a 10 one!!! They made a scene under water with the real Alyssa (not a stunt) and with lots of fishes swimming around her. It was great. Then we saw the exterior scene in with the fishmen :D That scene was great too! I love exterior scenes... But, that is nothing compared with the final scene in the cave! The three of them flying to the walls, Piper getting under water, and the whole scene was so awesome! That is a reason to say that this episode is 10...We usually don't see these kinds of scenes in Charmed, it has a lot of action there. More things? What about the Necron torture... I mean when Piper is being electrocuted! It was just plain perfect!
So... what about the story? To me the story remember barely to "Look how is..." First one sister goes out, then another one do it aswell, and only one sister is left to handle the situation. Phoebe idea of beging a marmaid was great, and the Piper with the spell backfire! Paige acting like the independent leader witch. GREAT! Besides, I loved the demon idea... Necron is so different, a skeleton being traped between life and death, it is not perfect? It was a really original being and the final explotion in the cave was awesome, despite the whole "it is very dangerours"... that was great aswell!
So, what do you want me to say? Great story and great action, a 10!