2nd phase is already released. And this is the strategy that I used to cleared all the map

?-5: from top to bottom : 1-1-1-2
?-6: same strategy as ?-5
?-7: from top to bottom, left to right: 1-1-1-2
?-8: from left to right: put your strongest squad on the first tent, and you all set. All you gotta do is pray for RNG, and the boss is pretty strong even thou it's only lvl 62 and he weaks against pierce type , so you might wanna arrange your squad before enter the map.