what it says in the title, where am I most likely to find all the monsters for the loot I need for that offering?
#Best levels to find the monster loot for the altar offering?
spare shadow
lime night
Varies by type of loot you need. I'd work your way through the mines, so you can encounter all the possible monsters, then go back to your besitary, and specific focus on the ones that give you the drops you're looking for.