Digicore can be used to exchange for other items such as clones, used for crafting and can also be sold. the price of the core is very expensive, on the omega server the price can be more than 11m.
then how to get a lot of digicores?
one way to farm core is to collect devil digieeg (mercenary) that drop from black Cherubimon(evil) in FIW (file island waterfront). Devil DigiEgg (Mercenary) can be scanned in pawnchesmon to get digiegg. scan digiegg to get data/digicore.