If you really want to clear stages, just follow guides on youtube. There're tons of guides using low-end squad. You may miss some originite prime because of not clearing some challenge stages, but you still get most of reward. The only thing you need to worry about when not having high-end squad...
In my opinion, if your wallet allow, and the mod help you a lot, which worth to be supported, so you should buy VIP. It doesn't matter how many mod you use. Because people usually play only 1-2 games at the same time, unless you don't need to work or study, just eat, sleep and play. So if people...
It's not too difficult if you have dozen of elite 2 5-6 star operators. But I've just replayed this game recently, and only have 4 elite 2. And the rest of my operator are not event max elite 1 level and level 7 skill because of lacking resources. I've managed to clear EX-7, but I don't think I...