Observatory
Observatory is a special upgrade in Loot Grinder, the free medieval idle clicker.
What it does
Astronomers spot meteors coming and shelter the peons, greatly reducing deaths in a meteor storm. (Astronomers spot meteors coming and shelter the peons, greatly reducing deaths in a meteor storm.)
Cost
It costs 1.80B loot and is a one-time purchase.
Why it’s useful
Fewer peons lost to disaster means your loot-per-second never craters mid-run — protection upgrades pay off as insurance on everything else you’ve built.