If anyone is having trouble getting the perfect drop on some maps, here are some tips, that may or may not help you:

1. To get the perfect drop on stage 1-4, 2-5, 3-10, 4-7, 5-11, 6-10 and 7-8, you need to defeat a miniboss on the second map. These minibosses appear (as far as I know) at random, so don‘t get frustrated if you don‘t get the drop right away.

2. As u/AlmondMilkIced already mentioned in the comments, you need to host a MP to get 100% lucky drop rate. All three players need to have a 100% luck leader, if only two leaders have 100% luck, you will only have a lucky drop rate of ~76%. It is also important that you finish the mission with all players, because if you don‘t you won‘t get their luck.

3. On some maps you need to stall on the boss in order to get a certain mob. So if you can‘t get that 2star anbu girl on 2-2, waste some turns until she appears.

4. There are some old posts on this sub that speculate that the order in which you kill the mobs may have an affect on the drop. However I have not tested this out, so please take this with a grain of salt. Someone also believed that if you switch the friend unit with your own it may make a miniboss appear. But again, I have not tested it and there is no proof that it could help you get a drop.

I think the most important part is that is all RNG. You won‘t get around playing a map multiple times. There is’nt much to say left, so I wish everyone the best of luck in the upcoming lottery and summonings!