See how much Def you get from your Aura Field. The possible Def on an Aura Field ranges between 235-285. If you have an Aura Filed that has 250 or lower def, you have a weak AF and may want to wait and see if you can find a stronger armor that won't drain your TP (i.e. DF field). A good Aura Field has at least 275 def in my opinion.