Talk:Los Vivos/@comment-74.68.157.38-20120414205253

I just found out that even if I don't fight for a level and just skip it by waiting for 2 hours until they disappear, the level still goes up (of course, it may stay at the same level, but the level up seems to be irrelevant of whether you beat it).

Which means, if you don't want to waste your force for levels that give you mostly N+ cards, you can just trigger the event and wait until they appear. From the forum, it seems like that you're almost guaranteed to get R cards and above including R+ cards from level 9 (S cards may require much higher level)