That is a very hard mission, I only just got by it after several attempts. These attempts took a lot of time, only to end in Game Over, but dammit the game is too good to let that stop me. I did read a quick walkthrough and found out what I needed to know, the key is a really stupid thing I should have noticed.
I kept losing the mission cause the Edelweiss got its ass fried, so of course the answer is "PROTECT HE EDELWEISS". What you're suppose to do is after taking out all the turrets and a few of the radiators move the Edelweiss through the map, blowing down the walls behind it after passing them, eventually stilling it at the last camp atop of the map. While moving it be sure to use an attack on the giant tank every turn, even if you think it's pointless.
At this point you need to get a few scouts up there too (this is very easy cause you can use the camp right there, I presume you'll have some free spots cause surely some of your recruits have kicked the bucket) and have them hide behind some of the ruins. Keep in mind not to just hide them from the giant tank tho, keep in mind Selvaria will be coming from the opposite direction.
Remember to keep the Edelweiss as far away from the giant tank as possible, one shot from the front of the tank and the Edelweiss goes boom. Upon taking out all the turrets and radiators (I took the last radiator out in fashion, I had one of my hidden recruits (the one who's a pacifist) run beside the tank (Selvaria was on the opposite side of the tank so she couldn't attack her) and climb up it and promptly threw a hand grenade in the final radiator, destroying it.) it's not over, yes really.
All this did was take down the tanks armor, you now gotta blow the shit out of it. But this is very easy with the Edelweiss and some Lancer's going at it. Just be sure to keep your lancers out of Selvaria's eyesight. I lost two recruits in this mission, two lancers, one of which was voiced by Steven Blum, sorry man. Also, if you haven't found out yourself yet this game has permanent death. If a recruit dies and isn't saved (by having another run up to them) in 3 turns they really die and you can never get them back (unless you of course restart, load a previous save, etc…). The soul exception to this is of course the main characters, they just retreat after 3 turns.
It's handy to use the save/load option in this mission, it can save you from having to restart it all over if you make a big mistake.
Hang in there, Kierkegaard.
