Overstock DNA Cube and Database Credits, and all the empty rooms.
I'd really wish we get to have a one-day/ hours frenzy once in a while where we can use the stocked DNA Cube and Database Credits to get Helix Rift event characters. Or else we just stock all of these Cubes and credits for nothing since every original hero is already 5 stars, while some players' Helix Rift heroes like Cleopatra, Apollodorus, Evie, or Jacob are still stuck at 3-4 stars.
As for the empty rooms, there should be an adventure room like the Supply Room where we can send heroes out for rare crafting materials, or DNA fragments for Helix Rift Heroes. Or we can have an alternative training room (Meditation Room) for levels where we put heroes in there for level up without codexes but relatively slow compare to regular Training Rooms.