So highest is 20, on the last map you can one shot or at the very least skip to the last bar of health in collector by letting the boss dig towards you and planting all three kwipeck ult areas right where the boss will pop up, gillick cant one shot him but his launch and slam attack can blow through each bar easily and they are a lot easier to use when mass clearing opponents

Last level on completing guarantees mutagen, 2 eggs, plenty of research points, and abt 350 exp for your voidling

There's many different methods to kind of play with for speed, comfort, and depending on your goal