Complex sentence: The corporation derives income from Medievia by effectively selling in-game equipment; players making sufficiently large donations are able to nominate game characters to receive special "donation items", each item having a certain minimum donation amount associated with it.
Split into simpler sentences: The corporation derives income from Medievia by selling in-game equipment. Players can purchase special "donation items" for their game characters, each item having a certain minimum "donation" amount associated with it.