First of all, Duel is free, but it is not completely free and is partially paid, so if you want to purchase a card or use other services, you have to enter a booster pass code to get a kind of preferential ticket called Duelist Premium
For most cards, it also has to be a certain type of energy. [14] If you have a Charizard out, it might have a really powerful move that requires four energies, says Maddock
If heads, prevent all damage done to this Pokemon by attacks during your opponent's next turn
That said, dealing 7 damage a turn to a player or permanent is a win condition or a removal spell each turn, so its definitely worth playing
2022-02-18 Phasing out doesn't cause permanents to leave or re-enter the battlefield, so no leaves the battlefield or enters the battlefield abilities will trigger, and Kaito's first ability won't trigger again at the end of a turn in which he phased in.