The most famous of rare events, Terraria Blood Moon, happens only at shiny night with at least one strong player in the crew. It comes unexpectedly, and your luck to be not far from home at the time it reigns.
Everything turns red, monsters flood the town, and even neutral bunnies morph into ugly sadistic creatures. They knock doors out and ruin walls sensing your close presence. You can’t skip this mayhem, only face it like a true warrior. Or, which is the most common choice among players, waste all the coins somewhere on the road and pray for this hell to end.