While I agree the concept would work better as an enchantment, they have considerably improved them since they first came out. They now provide a small amount of culture (this event is the first one where they've had that feature) and they increased the percentage boost as well (the mage multiplier one went from a 10% boost to 50%) and they stack if you have more than one placed. The 5 day limit makes them most useful for tournaments. You just place them at the beginning of the tournament and they last the entire 5 days. Example: Mages are key units for marble and gems tournaments; next week's tournament will be gems and that is my Tier 3 boosted goods. So, place the mage multiplier and the unleashed unit buildings at the beginning of the tournament and it should help me clear more provinces, increasing my relic rewards and raising my gem boost as well as all the extra KP, spells, runes, broken shards, etc. For fellowships who make tournament participation their main focus and try for the 10th chest regularly, several members having some of these buildings can almost guarantee they get the 10th chest (and the accompanying blueprint!). Granted, those fellowships are usually made up of 'diamond' players (those who spend real money on the game to advance their individual and fellowship ranking) because the blueprints help with upgrading premium buildings without spending more diamonds. But I'm really happy to see those players get some perks since I look at it as they are paying for me to be able to play free (or in my case at a reduced rate; I'm just not patient enough for free, lol!).