21's and 15/20/25's

21's = 7 full reps, 7 top reps (just curl from 1/2way), 7 bottom reps(opposite of previous)
15/20/25's = do whatever weight which causes you to fail at 12, then rest for a few seconds and bang out the last 3 to equal 15. Drop some weight and do the same and end at 17, then bang out the last 3, repeat foir 25's. It may take a couple workouts to find out which weight works for you as far as when you fail.

I find these 2 workouts make my biceps burn the most, without them I never feel that I have a good bi workout