Storm Cellars
Storm Cellars is a special upgrade in Loot Grinder, the free medieval idle clicker.
What it does
Underground shelters protect peons from tornadoes, greatly reducing deaths. (Underground shelters protect peons from tornadoes, greatly reducing deaths.)
Cost
It costs 1.50B 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.