Synthesize and Disassemble

Once you get a character to p50 (and maybe some other cool requirement like completing certain tomes), another button appears under the bloodweb in the menus. See thread title. This will allow both killer and survivor to convert addons, offerings, and items from one rarity to another. But the fog is a fickle thing, as always, and there is randomness. Basically, you "sacrifice" a number of things of one rarity in exchange for another random thing of a different rarity.

Survivor items only convert to other survivor items. Addons only convert to other addons. Offerings only convert to other offerings. You cannot receive nor disassemble event offerings or items.

In Synthesize mode, it takes two brown things + 500 BP to make a yellow thing. It takes two yellow things + 1000 BP to make a green thing. It takes two green things + 2000 BP to make a purple thing. And it takes two purple things + 4000 BP to make an iridescent thing.

Disassemble mode goes somewhat in the opposite direction, as you would expect. Sacrifice an iridescent thing + 1500 BP to get a purple thing. Sacrifice a purple thing + 800 BP to get a green thing. Sacrifice a green thing + 400 BP to get a yellow thing. Sacrifice a yellow thing + 200 BP to get a brown thing.

Once a character reaches p100, they unlock Advanced Disassembly, which pretty much means sacrifice two things and double the BP, get three random things of lower rarity.