As you know, Builders are the workers that live inside the Builder's Hut. They upgrade, build, and rebuild structures. Gems are the premium in-game currency used to advance players' villages. And you need Gems to get more Builders.
Wizard Tower: The Wizard Tower is perfect to destroy groups of troops due to its high rate of fire and splash damage. It is complementary with Mortars. Put your Wizard Tower next to your Storages to defend Barbarians and Goblins.
Wizard Tower is suitable to deal with tier 1 troops. But Heroes especially the Queen will weaken its advantage. The X-Bow will not be taken down by the Queen. The Wizard Tower is better than the X-Bow in this situation.