The blood moon mechanic in Breath of the Wild is a key part of the game. Early on, the blood moon can just feel like a way to make the game harder. But later on, it’s clear that each blood moon provides a chance to get valuable resources. This post describes a simple way I use to keep track of the blood moon cycle. It also describes an odd glitch where the blood moon reset occurs without the cut scene playing.
Giant ancient cores are one of the hardest items to obtain in Breath of the Wild, but also pretty essential for acquiring and upgrading important weapons and armour. This post explains one reasonably fool-proof and safe way to farm them. The drop rate of giant ancient cores in this location over time is 1 in 8.