Nintendo's The Legend of Zelda: Breath of the Wild reimagined everything that was commonly associated with a Legend of Zelda games. From open world exploration to new mechanics like cooking, BOTW introduces many features that had previously never been seen in the series. One of the other major additions to the game was the active day and night cycle, and with it came the Blood Moon. This lunar event occurs whenever there is a full moon in game, but the Blood Moon's origin has yet to be fully explained. Luckily, the upcoming Hyrule Warriors: Age of Calamity may be able to help shed some light on the matter.
On the night of a full moon, the Blood Moon can be seen almost immediately. The bloodshot moon slowly makes its way across the night sky after the sun sets, and once midnight strikes, the skies begin to turn red, the clouds start to travel at a rapid pace, and little bits of malice can be seen flying through the air. This is when the Blood Moon officially activates. All across Hyrule, slain enemies will begin to come back from the dead and repopulated the land. The Blood Moon is meant to help players by respawning weapons and different monster parts, but it's also one of the most ominous new features introduced in BOTW.
There aren't very many details provided about the Blood Moon, outside of a short clip that plays when the Blood Moon appears for the first time in The Legend of Zelda: Breath of the Wild. A frightened Zelda warns Link of the coming Blood Moon saying, "Ganon's power grows...it rises to its peak under the hour of a Blood Moon. By its glow, the aimless spirits of monsters that were slain in the name of the light return to flesh." This quote might not seem like much, but thanks to the trailers for Age of Calamity, it may actually be quite revealing.
BOTW's Blood Moon May Have Been Created When Ganon Took Hyrule
Hyrule Warriors: Age of Calamity will tell the story of the events that led up to Breath of the Wild, also known as the Great Calamity. From what is already known, Calamity Ganon used its power to take over Hyrule and defeat the four champions, the King of Hyrule, and, nearly, Link. Zelda then uses her powers to seal Ganon inside of Hyrule Castle until Link can return to defeat him. BOTW revealed details of the Great Calamity, but Hyrule Warriors seems like it will gives players a first-hand look at the disastrous event. Trailers for the game have shown Calamity Ganon swarm Hyrule Castle as enemy Guardians begin to lay Hyrule to waste. During Ganon's siege of Hyrule, a Blood Moon can be seen hanging in the sky. It's difficult to tell for sure, but this may have been the first appearance of the Blood Moon in Hyrule.
In BOTW, Zelda warns Link that the Blood Moon causes Ganon's powers to rise to their peak. From the demo for Age of Calamity, it's clear that Ganon's forces are trying to take over Hyrule, but have been held back by Zelda and her army. Something happens between Age of Calamity and BOTW that shifts the tide of the battle and also creates the Blood Moon, and common sense would guess it's the Great Calamity. It seems the Blood Moon may be a remnant of the Great Calamity, which is why Ganon's power spikes during the event. When Calamity Ganon emerged and took over Hyrule, its power was so great it was able to project part of itself onto the moon, creating the Blood Moon. Enemies rose from the ground under the light of the Blood Moon on the night of the Great Calamity, similarly to how they return from the dead in BOTW.
This all just a tin foil hat theory, but it seems like a believable explanation for the origin of the Blood Moon. Zelda fans hoping to find out for themselves will just have to pick up a copy of Hyrule Warriors: Age of Calamity when it hits shelves November 20th.