Multiple combatants
When the PCs face multiple foes (and they often will), break up the action into multiple smaller engagements—the Ranger fights one crinwin, the Fox fights another, the Marshal and his crew deal with the rest of them. This isn't anything formal. It's just a natural way to manage the scene.
Unengaged foes—those that aren't pinned down in combat—are all sorts of potential trouble. Incorporate them into your moves whenever you have the chance. Announce trouble and have them move to flank the PCs. Demonstrate a downside of being outnumbered and have them block a PC's path. Reveal an unwelcome truth and have one come out of nowhere and smack a PC when they roll a 6-. Bad guys don't just sit around waiting to be attacked.
When a PC or follower engages multiple foes, make more aggressive moves than when they face a single foe. If they ignore the threat posed by multiple foes, tell them the consequences and ask. If they carry on and ignore the threat, or roll a 6-, or otherwise suffer the enemy's attack, then make your move extra hard.
When a PC or follower's attack could feasibly hurt multiple foes—because of the area tag, because a group of followers is making or Aiding the attack, or just because the player describes it in a way that makes sense—then the player rolls to Clash or Let Fly just once, but they roll damage separately against each foe.
When multiple PCs and/or followers attack a foe at once, one of them rolls Clash or Let Fly and the others Aid. If a group of followers attacks a single foe (or a significantly smaller group), they effectively Aid themselves.
When multiple combatants deal damage to a single foe, roll one combatant's damage (usually the best one) and add +1 extra damage for each capable attacker after the first. Apply tags from all the attackers as they make sense. For example, if a PC fights two Hillfolk warriors (d8 damage, 1 piercing) riding horses (d6+2 damage, forceful) and suffers their attack, you'd probably roll damage from one horse and add +3; that's d6+5 damage (1 piercing, forceful). Ouch.
Clever tactics can make a huge difference when dealing with multiple combatants. Holding a chokepoint reduces the number of foes they have to fight at once. Focusing fire on a tough opponent can help drop it more quickly. Attacking a group's flank and dropping some of them before they can react? Golden.
Rhianna, Garet, and Eira (two of her crew) find Caradoc barely holding a doorway against six crinwin. Some turn and hiss. Rhianna says "We draw hatchets and wade in!" Her crew are archers but not warriors, so she spends 1 of her crew's Loyalty (see Loyalty to get them to follow her lead.
Caradoc's got two crinwin occupied, so I tell Rhianna she'll be dealing with the other four. "How are you doing this?"
"I'll take point, chopping the first one and plowing past him to get at the next. Garet's on my left, Eira's on my right, a step behind, each hacking at one of their own."
"Sounds like Clash with Aid from your crew," I say. "But they're not providing advantage—they're letting you fight multiple foes at once." Rhianna rolls an 8. She and her crew deal their damage but suffer the enemy's attack.
Rhianna rolls her 1d8 damage twice (once per crinwin she engaged), getting a 7 and a 2. Crinwin have 1 armor and 3 HP, so the
first one goes down and the second is up but injured. She also rolls her crew's 1d6 damage against each of the other two crinwin, getting a 4 and a 3. Garet drops his, Eira's is badly wounded but still up.
They also suffered the crinwin's attack. I don't have a particular move in mind, but I know it'll deal damage, so I start with that. "Rhianna, each of you takes 1d6 damage from the crinwin you're fighting. Actually, you take 1d6+1, because you fought two of them."
"Really? Didn't I cut the first one down before it could hurt me?"
I could tell her that it got a lick in before it went down, but whatever. "Good point. 1d6 damage to each of you." She takes 4 damage herself. Garet takes 1 and Eira takes 5. They're all still up, but Eira's in trouble. I let that inform my move and I put her in a spot. "Okay, so Eira got tripped by hers and it's on her chest, smashing her head against the wall. She looks out of it and, Rhianna, you've still got a crinwin in your face. Meanwhile, Caradoc…"