Thorns on the Iron golem is not an aura, cuz it works only on the golem.
Iron golem is the best only if you have plenty of high runes to use, and you summon it from a beast axe, to make him have the fanaticism aura. But if he dies (or if you die), you will loose all the runes, so it's a very expensive solution.
But now there are some cheap runewords with good auras like Sanctuary or Meditation that can be helpful if you summon a golem from an item with those runewords.
Oh, you don't have to max the iron golem if you choose to use it: max golem mastery instead, and put 1 point into summon resist.
However, if you don't like the iron golem solution, use Clay golem. It has the ability to slow enemies of a very good %, so it's very useful in boss fights and it's very helpful cuz it's a great meat shield... it has tons of life, if you max it (in this case max the golem, not the mastery).
