I was thinking we have wood, stone, and gold keys. But there use is a little slim. However I have an idea of how to make keys more useful.
A chrome key allows a player to unlock a pack crate. A pack crate constrains a random item from one of the selected packs. This would allow players who can not afford crowns to still earn the crown gear by paying for membership.
Since ya would need to farm this components, and that requires time- in turn requiring membership: which allows king isle to make money, but provides satisfaction of using the drops ya would not use for something ya would want.
How does it work?
There are 13 tiers of crates available, one for each 10 levels. (Loot drops are class restricted). When a crate is opened it will randomly select a pack, and from that pack it will randomly select 4 pieces of loot. Crates can also be bought for crowns for 200 crowns.
So what is the recipe for keys equal to their level :