Oh, campfire 3 and 4! Oh the 5/6 ghosts (ranged elemental damage units) spawning all over the field! Oh the joy! Oh the torment...
Well, these levels are freakishly hard, ever incrising difficulty. The sheer number, power and frequency of the ghosts is just mind-blasting. And just for the heck of it, at campfire 4 all levels include a Bone Wall on the AI's side, preventing you from heroic rush.
Because of all the attribute of these strong ghosts you'll be in trouble, but this laso means you1ll have to only once evolve a working tactic against them.
There is a big help though: a recent event provided Velyn, a magic-immun elf card. Now THAT makes your life oh-so-much easier if you have it, especially for the last stage of the 4th campfire, where each line has 2 adiacent Bone Wall, preventing the ghosts from advancing! And as they do not have vigilance, and they are exclusive for these campfires, at least for this final fight you'll have an easier time (unless you fill up the bottom row with Inspire Ability units or something).