Rusted Key

The Rusted Key is a new item in Risk of Rain 2.

Whenever a new stage is entered, a Rusty Lockbox will spawn with the rarity of the contents based on how many Rusted Keys the entire party had when entering the stage.

This item is unique in the fact that it doesn't modify the current stage and is quantified by all keys among the team rather than an individual.

Lore
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.

Math
To understand how the Key affects the chance on a specific rarity of item, one first needs to understand how a normal chest chooses an item: A normal chest adds 80 chances for white, 20 for green and finally 1 for red. Then the chest, during its creation, uses this weight selection to select the rarity of the item. After choosing the rarity, it chooses an item at random from all available items from that tier.

The Rusted Keys multiply the chances of the green tier by the amount of keys the team has.

The Rusted Keys multiply the chances of the red tier by the amount of keys the team has squared.