I would have to disagree with this, since Spirits currently drain more MP from you then leaving out an avatar. Sure, you have to spend 170 mp to use a BP, but on something that is too weak, or even DC, id do that any day of the weak to deal out 1.5k-3k dmg while your spirit is still casting Rasp, and waiting for the casting timer praying it does a top tier aga which will still do like 300-500 dmg. So in the long run you end up wasting more mp for less results trying to attack low lvl things with a spirit.
The only time i ever use a spirit is if a monster im running from is sooo close that I cant get Garuda out in time. So i cast a spirit to run away.