When you purchase this key, you get to choose which of the 19 items you want. This is not luck based.

In the server, you can choose one of these:
1 Amethyst Sell Axe (Instant Sells All Items in A Chests) (self destructs after 3 days)
1 Amethyst Drill (Breaks 9 Blocks At Once) (self destructs after 3 days)
1 Amethyst Multitool
1 Swift Minion