I just randomly destroyed stuff and succeded.
same . I did use E all the time, so maybe thats the problem. using e or mouse2 button will pretty much let you avoid getting any hits at all ( imo ballista arrows are way too slow to even make it challenging) + you can get much moar ahead of your zeppelin .
i just stoped infront of the fortress, waited for balistas to shot at me first than i "rushed" with E infront of them burning 3-4 out and rushed back , waiting for balistas to shoot at me again & repeat the drill . Use healing zeppelin help and fireblast(??-the fireball thing) ASAP do not wait .balistas have the same shooting intervall all the time so all you need to do is to get to them while reloading. and even infront of them you have a big chance of sucesfully doging them by using E . Your priority should be the nests , electro tower (i mostly let zeppelin to take care of those and rushed onto ballistas) and than balistas . Hopefully this helps, it seemed very easy to me .
