This Weakaura will only be active in Naxxramas. While it's activated it will automatically roll on every Item according to your customized presets (Custom Options Tab).
You can change every preset to your liking and also add new items by item-ID with a roll preference under "Custom Item Rolls". Some custom rolls are already set i. e. for Runenloth, Major Healing Potion and Major Mana Potion.
Default Settings:
Grey: Pass
White: Pass
Green: Need
Blue: Pass
Epic: Pass
Legendary: Pass
Scraps: Pass
Word of Thawing: Pass
Custom Rolls:
Runecloth: Need
Major Heal & Mana Potion: Need
Be careful when you reset the WeakAura to its default options your custom added items will be deleted!