Rusted Key

The Rusted Key is an unlockable common item in Risk of Rain 2. When a player has this item, a Rusty Lockbox spawns somewhere in the next level. The Box contains an Item, the rarity of which is determined by the amount of Rusted Keys all the players have when any one of them opens a box.

The Rusty Lockbox is quite small and easy to miss, but it's dark color and rectangular shape usually make it stand out. In a multiplayer session, the Lockbox can be opened by any player as long as one player has at least one key. Opening the box costs nothing, and will trigger Bundle of Fireworks.

Having more keys won't increase the amount of Rusty Lockboxes. Instead having more keys increases the chance of rarer items

Unlocking
The Challenge Keyed Up unlocks this item.

Shipping Details:
Order: Key Tracking Number: 12****** Estimated Delivery: 01/21/2056 Shipping Method: Standard Shipping Address: |||||||, Druid Hills, Earth Shipping Details:

I don't trust UESC. Not one bit. Their security Chests?? Full of overrides and backdoors- I've got a cousin working in their factory, and they've got all kinds of weird things going on in those chests. I've seen so many of them in auctions - for the lost and unclaimed ones - and you just pay money, and it springs open on the spot. Are you kidding me?

Anyways, I'm sending you exactly what I said I would - but it's too important to leave the security up to the UESC. So I'm sending the key to you - and the lockbox to Margaret. Like a two-factor authentication. Let me know when you get this.