Any Heirlooms in the "Temporary" section will be recycled for Nullifium on portal. Your Equipped Heirlooms will always stay with you when you Portal, along with any Heirlooms in your "Carried" slots. Nu is not spent, but dictates how powerful each of your Heirlooms can be!
You can upgrade any Staff and Shield to HALF the value of your total earned Nu. The currency to upgrade and replace stats, Nullifium, or Nu, can only be gathered by recycling an Heirloom. You can also click on the Heirloom's name on this menu to rename it, or click on the icon to change it. You can click a stat to upgrade or replace it. Only equipped Heirlooms give you stats, and you can only have one of each type of Heirloom equipped at a time. Once you've selected an Heirloom, you can Equip, Carry, or Recycle it. You can click on the icon of any Heirloom to select it. This way, new heroes will catch up faster to your older. The awakened hero is randomly chosen, whereby heroes with a lower awakening level have a higher chance of being chosen. You can awaken a hero for 500 arcane crystals. You can see your current hero awakening information in the Hall of Heroes under the Awakening tab. You will earn one Heirloom every time a Void Map is completed, and you have a better chance to get higher rarities if you complete the Void Map at higher zones. Awakening is a way to levelup your heroes by spending arcane crystals. Heirlooms are powerful items that can drop with a variety of bonuses and a variety of rarities.