Yeah so the simple way to do 4-1 like i said is to try to get a squad to that RNG pest on the left side, before the other squads beat the final boss.

The simplest way is super slow but super strong ally on the left side, since that route is the shortest and has tornadoes, and ally goes last. Then 1 super strong and fast squad and 1 relatively strong but slow squad on the right side. Hopefully 1st squad will reach RNG pest, and the 2nd squad if it reaches the boss too fast maybe it will be defeated first.

If you need more squads, like trying to get 2 squads to pass the RNG node, 1 and 2 should be strong, and 3 and 4 should be throw-away weak and slightly slower than 1 and 2. 1 should pass RNG node and either miss the pest or hit it, then 3 should reach the boss and die, then 2 should go to RNG, then 4 should go to boss. 3 and 4 might switch positions if 4 goe through all those tornadoes and 3 does not. If your squads beat the pests but can't beat the boss, the super strong ally should be able to finish it up.

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And same for me, 4-2 and 4-3 were much easier.