Artifact Fragments!!! So that people, particularly newcomers, can decide for themselves which building they want to evolve, instead of having a few random artifacts thrown at them in a lottery in the Spire.
I do understand that the developers are trying to preserve the rarity value of artifacts, so as not to offend the players who paid real money to evolve their buildings - but if we got lots of tiny artifact fragments in different game modules, like spire, tournaments, events, FA waypoints and even a daily log-in bonus, we could collect for several months and eventually make one Artifact that we REALLY wanted.
The designers could preserve rarity value by setting a realistic exchange rate for the fragments, that would make crafting an 'Universal Artifact' hard, but not impossible.
I do hope one of the designers is listening to this suggestion!!