When you purchase this key, you get to choose which of the 4  items you want. This is not luck based.

In the server, you can choose one of these:

1 Amethyst Drill (Breaks 9 Blocks At Once)
1 Amethyst Sell Axe  (Instantly Sells All Items in A Chest)
1 Amethyst Multitool (Can perform every tool)
1 Swift Minion (AFK For You, Auto Sell Spawners)