Is depicting the horrors of death, Barzakh, the Angel of Death, the Qareen (companion Jinn), and Hell prohibited, or can it be a means of guidance? And which is better in Da’wah: encouragement or intimidation?

If what is mentioned is a portrayal of the infallible ones among the angels and prophets, then it is not permissible. However, if it is a portrayal of a vision seen by a person in their dream, and they enacted it to clarify the image and increase the lesson, then there is no harm in it, as long as it does not portray angels. The best method in Da'wah (inviting to Islam) is what came in the Quran and Sunnah, combining both encouragement (Targhib) and warning (Tarhib) together.