The Temple allows you to summon and gain powerful items. You will also get a free Relic from visiting it daily!
Within the Temple there are several Altars. You can use your Gems to purchase from them and you will be able to get random types of Relics and Titans.
From time to time, the game holds Altar events wherein special Titans and Relics are added on the altars and will have a higher chance of getting them.