It was a rather roll heavy session and one player was late, so not too much happend, but it was still very satisfying.
So the players returned to the ark, warned everyone and tried to come up with as much defenses and battle plans and tactics, as they could. The Gearhead wanted to build some explosives and use them as sorta mines, so I allowed him two rolls and he game up with a 6er and a 9er explosive device. I then had him roll Comprehend to find some good places on the approach towards their ark, and he rolled good on those, too.
The stalker convinced the arks other four NPC stalkers to hide out in the zone, along the street that the other arks war-busses would drive along, and form a signal chain with mirrors and hidden signal fires in case if they arrived after dark. He also devised a battle plan how the stalkers should sneak towards the busses from the sides and back, and once the battle started harrass the enemies with sniper shots. Not nessessarily killing enemies, but sowing panick and confusion among them, so that they had to watch their backs and couldn't just concentrate on the ark.
The Fixer negotiated between the bosses, forged a truce for the time and whipped everyone into a good mood.
When the other arks three busses full of gun-toting mutants arrived, everything fell in place. The Gearhead rolled for his explosive devices: the 6er bomb did no damage, but the 9er rolled enough successes to damage one of the busses, blasting of some armor plates and giving the bus a limp, that I reduced the other arks battle rating by one. At this time my players ark had 3 battle rating, the other ark had 3 battle rating, plus I gave them +1 gear bonus for being the better equiped faction.
The Chairman then rose up via a platform on the roof of one of the busses, surounded by half a dozen of his children (he all had defensive powers on hold, so to speak) and gave a big speech along the lines "War. War never changes. War will forever be the scourge of humanity, that even ravaged this planet. But War is also the flame in the hearts of men, that will always push us forward towards greatness and mere survival. My people are used to war, are yours? War is bloody and disgusting business, and you will have to mourne many dead, if you stomp your puny defenses into the ground. But it doesn`t have to be this way. Give us ten of your numbers, your choice, and we will leave you in peace. Reject this offer, and you will pay a blood price way, way higher then that."
The Fixers player answered and gave a speech about morality contra depravity, and that living in shame and canibalism was the worst and most despicable way of living, barely above vermin. HE would offer them to reject THEIR evil ways and come back into the fold of humanity, by letting the players ark help them with agriculture and building a noble and stable society. After some back and forth, the player then used his power of pathokinesis with 7 MP, but also rolled a misshap and was hit himself. Both, the fixer and the Chairmain, and about three of his children, went down, hit by an invisible wave of imensive power. The Chairman was barely conscious, held his head with one hand and hatefully ordered the attack. I further reduced the other arks battlerating by 1 point, because their general was out cold, and so we rolled off 3 vs 2. The players go no successes, the other ark rolled ... two fails and rather uncoordinated charged the players ark front door, while sniper fire confused their back line, which took shelter in the bus, and after a few confused minutes of fighting with the defenders on the wall, the other arks assault troopers hunched back to their busses and drove back home with the tail between their legs.
This worked really, really well and was a lot of fun. After the battle, 6 mutants had died, but they died as heroes, defening their home and their loved ones, and not feeding a dehumanized engine of hate and depravity.
So, next session the players will lick their wounds and look for allies somewhere in the zone. They found the sinkhole during an earlier expedition, but didn`t feel brave enough to decent, but they had seen people there.