Imaculata
Hero
I see no problem with letting the players call the city guards when in a city. But eventually they'll get into situations that the guards cannot handle, and calling for reinforcements would make them responsible for the deaths of those very guards. And of course there are also corrupt guards.
My players planned a raid on a shipyard at some point, and they called in all the allies they could muster. Rather than having the npc's fight the whole battle for them, I told my players that the reinforcements would fight the majority of the enemies in the background, but that I would be zooming in on their own personal battle. So narratively speaking it was a collaborative effort (all the npc's took part), but gameplay wise it still came down to a battle between a bunch of baddies and the players (with no npc's involved at all).
Another example was a fight where the players organised an army of dwarves with rifles to help fight a massive creature in a lake. I used swarm rules for the dwarves, where each odd round they would fire off a volley of shots at the creature. However, if the dwarven leader was compromised, they could break morale. So this actually added an extra objective to the battle that made it more interesting.
My players planned a raid on a shipyard at some point, and they called in all the allies they could muster. Rather than having the npc's fight the whole battle for them, I told my players that the reinforcements would fight the majority of the enemies in the background, but that I would be zooming in on their own personal battle. So narratively speaking it was a collaborative effort (all the npc's took part), but gameplay wise it still came down to a battle between a bunch of baddies and the players (with no npc's involved at all).
Another example was a fight where the players organised an army of dwarves with rifles to help fight a massive creature in a lake. I used swarm rules for the dwarves, where each odd round they would fire off a volley of shots at the creature. However, if the dwarven leader was compromised, they could break morale. So this actually added an extra objective to the battle that made it more interesting.