Void Storage

Introduced in the 4.3 Dragon Soul patch, Void Storage allowed players to store all their gear for transmog without it taking up all of their bank space.

It was pretty much made worthless by Legion adding the wardrobe so that players no longer had to hold onto gear they wanted to transmog to.

Has one use in Legion actually, this is where you store your shitty Legion Oranges that you never want to see again.

Shortly before the 4.3 patch that allowed void storage Atena showcases all his saved tier sets and the state it's put his bank into.