Yeah i did read that they "count" towards next layer but not that they are "used" which are two entirely diffrent things. And removing previously aquired updates is kind of an anti-pattern, especially when next layer is basically the same xd
I have just one question, why my wind/dark unit has 1.2k less dmg than my other units on level 91? It was like this from very first levels and I trained my every unit the same way. Anyway, cool game :)
probably the balls killed you, you need to purchase the barrier