Disclaimer: I am a noob so take everything I say with a grain of salt.
Final mission of the campaign is go into the cellar and liberate the hostage by killing all the bad guys. Easy and standard right? Wrong! This mission is at least 10 times harder than any mission I have ever done before. I have once before lost one merc. In this mission on my first attempt I lost my whole squad, and it wasn't even close. There are military juggernaughts who take heaps of shots to take down, elite commandos that you can't spot until they gun you down, heavy gunners that strip your armour fast and all sorts of other nasties. Wow what a cool challenge, I can't wait to go back and try again. In the second room there was a guy who with two bursts ripped my armour to paper leaving my main merc defenceless for the rest of the mission. Loved this mission!
I went in the second time totally paranoid, creeping everywhere very slowly, taking a million turns very different from my normal charging style, ambushing guys around corners and even blowing up guys with the occasional LPG bottle carelessly left lying around. Result: I won easily this time. It was a very fun mission that needs a lot more thought as the enemies are very dangerous, at least for my level of mercs (Gasket was 19, Maddog 23 and Invader 24).
Attempt number/Dropped in mission/reward at end of mission:
1/ Winter Jacket uncommon/ nothing.
2/ 3 x ammo, Winchester 1873: Junk/ nothing.
3/ 2 x ammo, Asprin/ bike parts.