Originally Posted by Neko

Mostly u buy N-gacha tickets. then roll them to level ur cards. Pero is useful :P

Also, try to buy them in between of the Events, since N-Gacha tickets cost you 1500 Pero during Events, or when you buy them in "5+1 packs" and only 1000 Pero when there is no Event currently active and you buy them one by one. Also, always buy them one by one, instead of "5+1 pack", since 5+1 Pack costs 9k Pero (1500 for one Ticket) and is, actually, the same thing as buying them one by one during Events, while they are 1,5 cheaper when you buy them one by one between the Events. (you can still buy up to 99 Tickets at once - just remember to take the "1 Key" offer, not "5+1" Pack.
Also, they once sold them for 100 Pero instead of 1000, so keep an eye for that too.
Personally i spend all my Pero on 1k Pero N-gacha Tickets between the Events, and only buy them during Gambit Events to keep my Pink Keys counter above 1000 or if i run out of N Gacha Tickets or get a Special Effect Card from Event Gacha during Gambit Events and I am currently out of Wildcards, required to max those cards out to lvlv 100 to get maximum Trophies Multiplier from them, or to change N Wild Cards for R Wild Cards, if i need more of them to open later level-up pictures of the card i like.