You can test a hero on trial at 6★ Special Summon tab.
Trial Hero can be used for 5 days with Lv.50 2nd awakened.
After the period ends, the hero will be sealed. But, if you collect 1,200 Essence of the Hero, you can use the Hero, and all level-ups, awakening done during the trial period will be applied as well.
※ Trial Hero cannot be used for Defense Team at Arena & Protective Deck.
※ "Mythical Potion" item can be used the designated 6★ Hero, and it has its duration.
※ When Mythical Potion is used, the hero will be "Mythical" rarity, 2nd awakened, and Skill Level maximum status. But it will not be applied for Arena Defense Team.