We would like to bring your attention to the description of the non-battle towers:
These towers are used for interaction between players and for more efficient collection of crystals. There are 2 types of such towers:
Gift — towers that you can place not only for yourself but also for the other players; these towers increase the amount of collected crystals
Souvenir — towers, which in addition to the crystals give unique items and rare crystals.
These towers, like the battle ones, are created and placed by players themselves. Such towers do not affect the combat system, and only increase the amount of collected items and crystals. These towers cannot be destroyed by other players.