Which Boss are you doing? And are you successful in it? Do you always get at least 30% damage? With PD and Cupid you should be able to do Boss 2 or even Boss 3. You may be using Dryad or Exec instead of Champ but, if not, buy Champ first. AC can help you survive 3 min against Boss if you can't otherwise. AC also very useful in Lost Realm. If you happen to have 4/5 or 5/5 Revit he would be very valuable in Arena, as well.
Immo on the other hand is great for HBM and raids.