New game mode: Hide Your Build
EDITED:
After some feed back I think this mode would work best with the following:
Champ stats and items are hidden. The store only contains consumables and a Mystery item.
You can only buy the mystery item (500 gold) or upgrade an item you already have. You can refund any item for 350 gold. Game is on Howling Abyss.
Some fun special items could include one that doubles the range on all of your abilities. One that gives 50% CDR (essential an URF item) etc.
Make everything over the top.
