Game uses energy and skip tickets. You can only skip a level a certain number of times before you need to pay GEMS to refresh it (or wait until the next day) so also good luck upgrading your runes. The gacha is a shard gacha, so you're paying gems and tickets to get PIECES of a character, with a very low chance at a full character itself. More power to you if that's your thing.
My biggest gripe is the login rewards. There's currently a 7-day sign-in event for newcomers on top of the normal daily sign in. Maybe it's a glitch, but after signing in every day so far I could receive the Day 3 rewards from the newcomer event (which is only 2 summon tickets, what a joke), but I was restarted to Day 1 of the normal daily sign in. How can I simultaneously be on Day 1 AND Day 3 at the same time???
It's little glitches like that, along with the lack of communication from the devs, that made me uninstall this game and just play Priconne instead. It really is basically the same game with different characters and less polish. Feel free to try it out if you want (or if you even can), but in my opinion this game needs some overhauls before it's worth it.