Hate is a very strong emotion, and it tends to last long, persevering when the currents and flow of other emotions have begun to ebb. Emotion is a fundamental tool in our craft used to empower and focus the will and intent of our workings. The more passionate our emotions, the more likely we are to experience positive outcomes with our spells and incantations. Caution must be exercised with hatred though, but this does not mean it should be shunned or avoided. Like all other emotions, it is a tool, and when used properly can be honed into a state of razor sharpness. Hatred in offensive magic can be the difference between a curse with the punch of a derringer, or the impact of a howitzer. Hate is very powerful indeed… but it often exacts a toll or price.
If you harbor hate long enough, if you feed it enough, it can control you versus you controlling it. Unchecked it can become a supernova of destructive power, but it can also burn you out, consuming all that you are from within, and devouring all those around you. If required, use it wisely.