The higher prayer, the better, same applies for defence If you want to start barrows early, get that mage to 59, complete family crest and get the chaos gauntlets, and use Fire BOLT on them (blast is a complete waste of money). If you want to do the more recommended Slayer dart method, then you should at least 70 mage, preferably 80+ try looking at satenza's guide for the lower level equip and such.