I am looking for a Fantasy/magic movie which looked really new and maybe watched it between the years of 2007-2012. From what I remember it was a movie about two worlds. These worlds could only be entered once every year from January to Halloween where the barrier between the worlds would close off from each other. (I might be wrong though).
There was also this school where people (witches, warlocks, all kinds of halloween creatures) went to and there was this headmaster who sought this magical gem/necklace inside of this box which belonged to some queen back in the past when the school might have been a castle.
This gem (pretty sure it was a Ruby maybe) which was turned into a necklace when used by a descendant of some family called "Cromwell" or something similar to this on halloween night I think has incredible powers or something similar along those lines which can basically if wanted can control anyone to your will or enslave everyone.
I also remember at the end, a trio of a guy, an older woman (maybe the protagonists mum who is a girl) and some other person) in the end chanted something similar to the lines of "the power of three" and blasted some type of magic which destroyed it forever.
Also the headmaster was in some type of evil organisation of witches and maybe warlocks and had been spying on this girl who had Cromwell or something similar to this in her name as she was a descendant who could use this gem.
Finally the last thing I remember is that this girl is pushed back in time to learn of some towns history and is thrown in prison and then meets the queen who looks exactly like her and learns about what's inside the box, the origins of the gem, what it can do and why she (the queen) locked it away in the first place and at the end gives her the key to unlock the box which is the moment where she is pulled out from the past and back to the future. With this she unlocks the box but then the gem is taken by the headmaster and on Halloween night, she is forced to use it otherwise some dog which I think was her brother transformed by three asian witches (I think), would die.
Does anyone know what movie this might be?