Go to the Graveyard and fear some lowbies while you watch a movie, or a football game. Use your single target fear, and your AE Detaunt to raise your Subj. Just cast fear, then AE detaunt (usually next to that big group of wussy skellys)... After that use your AE damage while you wait for your timers to refresh... rinse repeat.
If you are seeking to raise this ability before hitting some harder content, that's what worked for me.