I wanted to revisit this topic a bit because some other similar questions have come up recently regarding use of Seize By Force. I think one really important thing to keep in mind when narrating the results and snowballing of Seize By Force is the choice that people make when picking options and what those choices mean in the context of what is happening in the fiction.
For example, what does it mean to "take little harm?" Is it not exposing yourself to fire? Is it diving for cover? Is it suppressing the enemy? Is it zigzagging movement? In my previous example I used happenstance - Carson's rifle jammed and he wasn't able to continue shooting, allowing Deke to escape with less Harm being taken. Similarly, what does it mean to "inflict terrible harm?" Is it concentrating fire on a particular target? Is it knowingly making attacks that are as ruthlessly damaging as possible? Or is it being very calculating and taking every possible advantage of the enemy's mistakes? Or is it just a really lucky shot? The truth is that it can be any of these, and they are all equally valid in the abstract. But when it comes to your specific fiction, the distinctions become important because they dictate what follows, how the moves snowball, and what the appropriate "next move" is going to look like. So consider what the options mean, and how the trade-offs that the players are making will influence what comes next.
Because an example always helps, let's consider the previous example of Deke throwing down against Abnett, Butters, and Carson.
Deke decides to teach these jokers a lesson: "Fuck this noise, I quickdraw my antique Colt Navy revolver, dropping and duckwalking to the nearest cover as I do, shooting the whole way. And when it comes to targets, you'd better believe Abnett is at the top of my list."
MC: "Great, roll+Hard"
Deke: "I got an 11. I want to 'take definite hold' of Abnett's fucking life. Seriously, I want that dude to die. Apart from that, I want to keep myself as safe as possible and scare the bejeebers out of everybody else to keep them out of the fight.
Deke is again going to inflict 2-Harm (ap) on Abnett as before (different gun, same armor-piercing rounds), only this time she's focusing the damage on him. Inflicting 2-Harm on an NPC is likely to kill him, but since she used one of her choices to "take definite hold of it," the MC decides that the damage is immediately fatal. In return, she'll take the 3-Harm from Carson's assault rifle minus 1 for her armor, minus one more for taking little harm. The MC narrates thus: "You drop and draw, and as you do so your first shot takes Abnett right in the crotch. He falls, screaming, and your second shot takes off the front of his face, thankfully ending his screaming with a final wet gurgle. Carson curses and brings his rifle to bear on you, letting rip as you dive for cover. You throw some rounds in his direction as you roll, upending tables to make as much cover as you can. One round catches you in the calf, but it's a through-and-through. Meanwhile, every other Tom, Dick, and Harry in the joint is kissing the floorboards and praying to whatever powers they hold dear. Go ahead and roll+Harm."
Deke: "Including the +1 gives me an 8."
Here the MC has an opportunity. He decides that because Deke chose to "take little harm" by ducking for cover that she has "lost sight of someone she was attending to," and narrates it this way: "Right, so you duck out around the table to drill Carson, only to discover that he's gone. He must have been moving too, because he's not where he was and you don't see him immediately.
Deke: "Well either way I need to reload. I suppose that's under fire from Butters if nothing else, yes?"
MC: "Believe it."
Deke: "Pssh, a 14. Half the new shells are in before the spent brass hits the floor."
MC: "Indeed, but you are still taking fire, albeit inaccurate, wild fire. You don't have eyes on him but Carson knows your general location and is spraying the area down. You roll over onto your back and pushwalk yourself across the floor to better cover, continuing to reload smoothly as you go."
Deke: "Right, so now that I can shoot him again, where the fuck is Carson?"
MC: "It sounds to me like you'd like to know your enemy's true position, yeah?"
Deke: "Fuck. Yes, rolling+Sharp nets me a...4. I really need to improve my Sharp."
The MC chooses to flip her move, i.e. to reveal her true position to her enemy: "Nah, you're just focused on the important work of reloading and trying to keep all the flying debris our of your eyes. Then there's a brief lull in the shooting, into which Carson shouts, 'She's over by the piano.'" This is the MC announcing future badness, letting Deke know what's up. "Butters yells, 'Yeah, I can see her!' 'Well then shooter her, you idiot!'"
Deke: "Time to move! Staying low I want to run across the room, if at all possible putting myself farther away from Butters and crossing Carson's line of fire more or less perpendicularly. I want to get him to reveal his position, but in a way that minimizes my chances of getting ventilated."
MC: "Sounds dangerous. Roll+Cool."
Deke: "Whoops. Bad time to roll a 9."
This is a success, albeit a partial one, so Deke gets what she's going for, mainly to bait Carson into revealing his position. But as a partial success, there's a complication, so the MC says, "You take off at a run, and sure enough Carson pops up from behind the bar, hosing as you go. He's not anticipating how fast you are, however, and his shots are all falling behind you. Unfortunately, your line takes you almost straight away from Butters, so he doesn't have to lead you as much, and he tags you with his pistol, two rounds smacking into the back of your armored biker jacket. You're looking at 1-Harm after armor, so roll+Harm."
Deke: "Hah! My shitty dice karma is on my side for once. I got a 5."
MC: "Right, so you pretty much cross the room. You're now closer to Carson than you are to Butters, and you're ducked down behind the edge of the elevated stage that the strippers use. Fortunately all the strippers are face down and screaming, so no one's in your way really. Carson has ducked behind the bar again."
Deke: "So he can't see me right now?"
MC: "Nope."
Deke: "OK, here's what I want to do - I want to vault up onto the stage and run across it. When I get to the other side, I want to dive at the bar, such that I'm sliding along it at a high-rate of speed. And as I pass I want to waste Carson. And once my velocity is spent I want to roll off behind the bar to get cover from Butters."
MC: "Wow. You're ice cold, aren't you?"
Deke: "I sure am."
MC: "Well that kind of move is pretty damn Cool, so roll it." The MC is a fan of Deke's character, and decides that this is a great excuse to showcase a player's stat substitution move. As such, he allows Deke's bold move to take Carson and Butters by surprise, allowing her to go aggro in the middle of the fight. But the fiction dictates risk here: "Just be aware that Butters might be able to take a shot at you if you're not quick enough." Here again the MC is offering an opportunity with a cost - if Deke gets a partial or a miss, she risks Harm.
Deke. "No worries. Fortune favors the bold, heh. An 11."
MC: "As you vault up onto the stage and run across it, dodging strippers as you..."
Deke: "No way, I step on those bitches if I need to."
MC: "...I mean, running across it on the supine backs of the screaming strippers, Butters's eyes look like dinner plates. You throw a couple of rounds in his direction to keep him honest, and he dives for cover. You leap across the gap between the stage and the bar head-first, scattering glasses and bottles as you slide along the wet bar-top. As you get to him, Carson looks up at you, shocked, his mouth a big round O. You put two rounds in it before you're past, coming to a stop and rolling off behind the bar close to the end nearest the door."
Deke: "Great! As soon as I can get my feet under me, I want to pop up, level my gun at Butters, and yell, "Drop it, asshole!"
MC: "OK, but roll+Hot because you're drawing down on him with an empty gun. You haven't reloaded yet."
Deke: "Oooh, but I'm dangerous and sexy! Can I make eye contact with him?"
MC: "Yeah, at some point he peeks over the top of a roulette table to see if he can see you."
Deke: "Great. I got an 8. I spear him with my gaze."
MC: "He freezes, total deer-in-headlights."
Deke: "Awesome. I want to walk over to him. Hey, can I reload as I go?"
MC: "If you roll+Cool."
Deke: "Hahaha, another 14."
MC: "Right, so this end of the bar is actually closed off, so you have to backtrack, stepping over a cowering Nabs and Carson's leaking corpse as you go. As you cross the room you keep your dead stare at Butters, boots crunching on broken glass, the tinkling of spent casings as you calmly reload, never taking your eyes off him. He actually stands up from his crouch and takes an involuntary step backwards. What do you do?"
Deke: "Once I've reloaded and I'm close, I level my gun at him, stick it right in his eye. He's still frozen, yeah?"
MC: "Yup. He's actually wet himself, tears welling in his eyes. He's mouthing the word 'please' but no sound is coming out. What do you do?"
Deke: "I gently reach down with my free hand and relieve him of his pistol."
MC: "No resistance, his pistol is yours."
Deke: "Great. Then I waste him, sashay over to the bar, drop his gun on the bar-top and say down to Nabs, 'This should cover any damages. We're square, yeah?'"
The MC is looking at Butters through crosshairs (nobody likes Butters anyway), and the fiction puts Deke in a position to simply inflict Harm. Done and done.
Right, so this is a very different fight, with much closer focus for the same opening situation, and predicated on different player choices. But it's still not a repeated Seize By Force over and over again. The position of the PC and the NPCs changes throughout the fight, largely because no one in their right mind stands still when getting shot at. That position has consequences. It opens up some opportunities and closes down others. This fight was one Seize By Force, one Read a Sitch, three Act Under Fires (two of which were predicated by the need to deal with her weapon's reload tag), and a Go Aggro. And had Deke not had the custom move, it could have ended with a Manipulate as she bluffed Butters with an empty pistol. Three NPCs put down like dogs and the other non-combatant patrons terrified of Deke the death-dealing dynamo - not bad for only rolling+Hard once.
Additionally, in this particular example, the MC allowed Deke to do something she was good at (Act Under Fire) to make up for something she was bad at (Read a Sitch) by exposing herself to fire as a way to draw Carson into revealing his position. Had she spotted him first thing, she'd not have taken that second point of Harm, at least not the way she took it. As the MC, look for ways you can offer these kinds of opportunities for players, just as you look for ways to put them in a spot. Deke was saddled with needing to Read a Sitch because of her other choices ("take little Harm") and the changing situation (as a result of her partial on the Harm move) altered her position within the fiction relative to the NPCs.
Whether you choose to zoom in or out is going to have a lot to do with the story you and your players are trying to tell. What is the purpose of this encounter? Does it set the stage for future badness, does it escalate some existing situation, or is it the culmination of part of a major plot arc? Answering these questions will help you decide which level of focus is appropriate. And if you don't have a good feel for meeting their expectations, don't be afraid to ask your players. Just be straight-up about it, and ask how detailed they want this particular fight to be. The more experience you get with each other as players and MC, the more of a feel for this kind of thing you'll develop, and you'll be able to give them interesting, challenging, exciting fights that involve more than just rolling+Hard.
But whichever way you choose to take the focus (close or far), don't skimp out on the narration. Because nobody remembers "that time I rolled+Hard and totally crushed it to shoot up Abnett's dudes." But I promise you Deke's player (and probably all the other players present) will always remember "that time Deke beer-surfed along Nabs' bar and shot Carson in the face."