If you are one of my players (Roy, Joe, Andrew and Lainie) please stop reading now, ignorance is the Emperor's grace.
When I first looked at Final Sanction I noticed there were a lot of fights, and all but the first one seemed to be the same. Taking the idea of Turning Points from the first battle I made a list of things to add if a battle seemed like it was dragging out. Enjoy.
Hostage Situation Tank! A rebel tank breaks through a nearby wall and opens fire. Millions of rats swarm up out of the sewer. (Precursor to a subterranean 'Stealer attack?) Shell-shocked civilian(s) wander oblivious through combat. Sniper! A well placed shot hits any one character not wearing their helmet. If the players do not kill the sniper they and their allies are at risk. Looters. Civilians take advantage of the battle to loot a nearby market or supply cache. Solitary enemy horde is actually a gang of survivors, not rebels. They disengage from any imperial force, take supplies from other civilians by force, and act to protect their families, which follow at a distance behind them. Red vs Red? One of the hordes is the above gang and turns on any nearby Rebel horde. Blue vs Blue? Heavy stubber fire tears through smoke from nearby fires. A PDF strongpoint mistakenly fires on the players. Building collapse. A nearby building is damaged from the fight and begins to sag. The players can lure the enemy in and then destroy it, or use its collapse to cover their withdrawal. APC! (See Tank!, above.) RPG! A rebel fire team has a Rocket Propelled Grenade launcher rather than a heavy stubber. An inaccurate weapon, it is a threat to marines and PDF alike. Fire bombs! Rebels attempt to hit the marines with makeshift fire-bombs. The relatively high AP makes them a threat even to power armor. One horde of Rebels are children throwing rocks. They could be screening a heavy stubber emplacement or used on their own to shock the players. Sudden Downpour. A cloudburst reduces visibility and allows the players and any of their PDF to disengage, even if the PDF have been "spent" to nullify a Rebel horde. Alternately, it could allow close combat units to charge in without taking much fire. Mutants! One horde are genestealer hybrids, armed as Rebels but with better close combat ability and Fearless. Diversion: A fuel truck tries to ram the marine/PDF position and explode while a rebel horde uses the diversion to launch a flank attack. Agri-harvesters trundle down the street, scything blades or churning threshers make short work of anyone caught in the way. Swamped! The area is suddenly filled with troop transports and confused soldiers, either fleeing something or rushing towards something.
There are only so many times marines can fight in a street or door to door through a building. Use these locations to add interest and tactics.
Holding Pens. The capital city of an Agri-world needs to move a lot of supplies without many vehicles. The battle takes place in or around the holding pens for a group of large pachids used to haul produce wagons. Massive Grain silos / troughs. Empty, these can be ambush points, full they can be an accident waiting to happen as one explosion spills tons of grain into the street or creates a firewall. "Hot Gates" A natural choke point; ally, rubble, sewer tunnel, etc allows the players to defend against many more foes than normal. It is also possible they could trap themselves if they are not careful. Nettle-Wings. An insect-jelly harvisting dome full of Nettle-Wings. This could be used as a distraction or a trap for either side. Marines beware, they try to burrow... Agri-silt spill. Fine grains, dried algae, flower, or some more exotic consumable fills the area. Very difficult going for something as heavy as a marine. A flammable dust, what could possibly go wrong? Spreading Fire. Civilians flee a fire that spreads through the area. Some civilians run back into the burning buildings to save belongings/pets/family members. What do the Emperor's Angels do? Crash Lander. An orbital barge has attempted to lift off from the space port and has either recently crashed or crashes in the midst of the battle, gouging up a hundred meters of cobblestone streets and demolishing a city block. Rescuing the pilots could give the marines more options in the future. But wait, what were they trying to leave with? Hospital teeming with refugees. Desperate people injured, tired and seeing their lives destroyed. Could this group in need turn into a riot if the marines do not help them? Or is it just another reminder of the price of war? Precinct House. Once an Enforcer precinct house, this heavily fortified prefab building is now filled with refugees who cannot fight and who are unaware of the buildings strategic and tactical uses as a bunker or HQ. Do the players kick the civilians out? What if the civilians are attacked while outside the walls? A well defended building in a useless position. A PDF unit has hunkered down in the middle of nowhere and awaits orders which will never come. If the players make contact and restore their morale they could have a place to rest or an allied PDF unit. But why did they choose this building? Vox of the Emperor station. The source of the vox jamming in the city. A public broadcasting station is in the hands of the enemy. What blasphemy do they broadcast? If attacked openly they will certainly be able to bring in many hordes of rebels to help them. Emplaced heavy stubbers dot the rooftop of this important rebel asset. One rebel general and one genestealer lurk within.
Have fun and post any entertaining scenes you run with them.