Yea of course you can do that, since UnholyFrenzy lasts longer then Bloodlust you ca put it on before battle. The thing is, if your playing good teams, it all comes down to takeing spells away, and not putting them on. So dont expect to be able to get all those bluffs on all your stuff. If you do get BL and UF on some of your units it will combine though. :-)