A unicorn seen in a dream is always a quite auspicious sign. The meaning of is often one of purity, especially spiritual purity though the interpretation can vary significantly due to various circumstances in the dream.
Simply seeing a unicorn in your dream signifies that you will quite soon meet a person which will gain your trust in a rapid manner. They are likely to become a lifelong friend of yours. The actual meeting will be rather uncanny and fate might have a strong influence. If this dream has a repeating nature it means that the person you will meet might even be a soul mate of yours.
Chasing a unicorn in the dream signifies that you should be careful of speedy decisions made in the upcoming period of time. You should also have upper hand over your temper as you patience will be tested especially in the personal life. This dream in general can be considered to have strong warning overtones.
Meeting a unicorn while hunting, signifies that you are quite reasonable and down to earth person. If this dream has a repeating nature it means that your reasonable nature will be soon required in solving a task in your professional life.
Hunting a unicorn in a dream means that your friendship with another person will be made uncomfortable due to the other person being involved into nefarious and possibly criminal dealings. There might a danger for your reputation being tarnished and you will have a dilemma whether to continue your friendship with them.
Feeding a unicorn in your dream means that your long time wishes about some aspect in your personal life will come true soon despite some obstacles in the way.
Killing a unicorn in your dream signifies that you soon have some sort of an emotional shock which will be related to happenings in your professional life.