The Legend of Zelda: Breath of the Wild has 120 shrines full of puzzle challenges to complete. In a total jerk move, some of the shrines can't be entered until you've solved some other, often complex puzzle. The shrine at Washa's Bluff is one such shrine.
Zelda: Breath of the Wild: How to solve "Under a Red Moon"
First, head here on your map. Washa's Bluff is a small plateau southwest of Ridgeland Tower in western Hyrule.
If you go to the exact point I'm standing at in that screenshot, you'll find a pedestal that's the key to this puzzle. If you listen carefully, you'll hear the telltale accordion of Kass, the game's traveling riddle bard. If you talk to him, he'll give you a riddle about waiting until the moon bleeds red and standing on the pedestal with nothing between you and the night air.
Let's cut to the chase: You have to stand on the pedestal with no clothing or weapons equipped during a Blood Moon. Blood Moons happen periodically whenever there's a full moon in the sky at night and it signals the respawning of every enemy you've killed since the last one. You can't force a Blood Moon to happen; you're beholden to the game's moon cycle here.
The easiest way to approach this is to drop a bundle of wood on the ground nearby, start a fire and wait until night. Keep doing this until you see a full, red moon in the sky. Once the Blood Moon shows up, the pedestal should start glowing. That means you're clear to strip down and stand on it.
If, for some reason, you don't have a way to start a campfire nearby, you can sleep at an inn or wait at a stable's cooking pot. Just make sure you keep waiting until night and looking at the sky until you see the Blood Moon. Once you do this, the shrine will show up. It contains a medium difficulty combat challenge rather than a puzzle. Be sure to stock up on food and weapons before approaching it, as always.
More Zelda: Breath of the Wild news and coverage
Find out all there is to know about Zelda: Breath of the Wild, including how to preserve your items, how to beat bosses like the Stone Talus and Lynel, the best recipes for Link and how to take on the game's shrines. If you're looking to snag a giant horse with little stamina, here's how you accomplish that. You'll also want to find out where all the great fairies are in the game, how to use amiibo with your version of Zelda and what went into making Breath of the Wild.