One of the two major flaws of this otherwise good game is the random drop rate.

Put every girl available like in the anniversary time, make them drop 1 after 100 victories against any troll, make a separate counter for the event girls, such as she drops after 100 victories against the troll that holds her and the overall quality of the game goes sky high.

Of course, they are too greedy and uniterested in making a good game that they will never make such improvement. Not even in the test server, where they have nothing to lose.

For those who are asking, the other flaw is pay to win. As you can see evry event has 1 girl from mission, which is good, 2 girls from trolls, which is bad because the drop is random, and 2 girls from epic pachinko only, which is bad because they are only available by spending, which, in a pay to win game like this equals to cheat.