OK, if offered the quest Prone Sweet Prone and you are not anywhere near Lv45-50 or lack a Skell with flight ability, don't take it. Quest summary will say you just have enter a fortress, find a key - defeat a Lv 19 enemy - release prisoners. What isn't mentioned is every other enemy is at least Lv 42 and hostile and there's some killer Lv 50 enemies with massively long sight lines! So, I'm currently stuck with a quest I can't do and that'll kill my Skell in 2 shots even on a stealth run. Going to play the long game, then, at a suitable time - I will return to that area and kill every single Prone and robot. There will be vengeance.