This film is about wizard or apprentices and was made in the late 1990s or early 2000s. It's about some sort of wizard or a school of wizards on an island in a lake.
A conflict starts because the protagonist (who is in a woods-type area) is persuaded (or rather teased) into talking to the dead using his newly found magic.
While he's doing so, at the convent we see a massive sealed door with all kinds of locks and bars on it. His love interest is among the nuns here and they try to keep the door closed at all cost. However, they can't and the door bursts open and evil spirits escape.
The next scene shows the evil spirits arriving at the protagonist and his "friends", and chaos ensues.
I'm pretty sure this movie was made for TV.