Increased initial creature growth rate.

I have a better idea. The Legion statue doesn't have to be kept in the Castle; it provides a bonus just by being with the hero. Do the same with all artifacts – they provide their effect to all Castles if they are with the hero.

The problem, in my opinion, is not so much about the need to keep the hero in the Castle, but rather about the insufficient bonus from these artifacts. Fragments will become an important element of the game only if they are at least as good as the "Niche."