I am just wondering if some of the later artifact challenges require you to have sets with specific stats to equip on champions?  I try to keep at least one piece of equipment for each slot, but I am not sure if I should be hanging onto more of the artifacts for later challenges or not?  Like what I mean in particular is if there are some challenges later on that might want something like "equip a support champion with 4 attack artifacts with HP% as their primary stat", or does it not ever get that specific?