I've been on the spiritual path for the last 10 years and recently I have intensified my practice which has jump started my spiritual life.
I have always had fears which I have tried to face as much as possible. Recently I was "attacked" by a spell of fear that lasted about 3 hours and I felt this intensity after a long time. After it went I realised that it is almost like a "possession" by a force, but the triggers by themselves are not as powerful.
Are there "beings" who enjoy paralysing us?
The important thing for you to look at in the situation that you have described is that the “attack of fear” occurred after you began intensifying your spiritual practices.
What holds us in delusion and separates us from God are the karmic patterns that are like seeds (or vortices) of energy in the subtle spine. Often when we make a deeper spiritual effort, these seeds germinate and release tremendous psychic energy.
This release of energy can cause us great confusion and suffering, because it brings to the surface of the mind patterns of blocked energy.
Ultimately, this is a deep blessing, because it forces us actively to deal with the issues that have long been present in our consciousness.
We have an opportunity when such things occur, to summon up the inner energy to go deeper in meditation and to try dynamically to burn up the negative quality of fear (or anger, or jealousy) by offering it to God.
Often in a short period of intense prayer and offering to God, we can burn up the seeds of past bad karma that have been troubling us, perhaps for lifetimes.
So, to answer the second part of your question: Yes, there are entities that attack us. I find it much more helpful, however, to use the model of burning up past karma as a step towards soul freedom.