Problematic wounds
A problematic wound is one with lasting fictional consequences. Characters suffer them when you hurt them or make another GM move that involves a character getting hurt in a specific, consequential way. Simply describe the wound in the fiction. It's now true! A twisted ankle can't bear weight. A blow to the head leaves them staggering and dizzy. A severed hand is severed, and they're probably bleeding out (and in shock). These sorts of problematic wounds should be particularly common when messy attacks are involved.
Problematic wounds often involve PCs marking debilities and always involve taking damage (i.e. losing HP). If an NPC breaks a PC's fingers, the PC can't make a fist, is probably weakened or dazed or miserable from the pain, and is going to take 1d8 damage (ignores armor). The damage won't kill them if they drop to 0 HP, but it could take them out of the action.
Announce trouble (future or offscreen): "Andras is white as a sheet, and that snake bite is red and swollen and you see angry red lines following his veins up his arm. What do you do?"
Reveal an unwelcome truth: "Oof. Yeah, Blodwen, you peel the bandages back from Garet's wound, and… it's not good. It smells bad, the flesh is kind of black, and there's a greenish pus. It's infected, and it's going to get worse. What do you do?"
Put someone in a spot: "It claws at your face before you hurl it away. Take d6 damage. You're still up? Okay, I think it gashed your forehead and blood starts pouring into your eyes. You can't really see, but you hear it scuffling about, getting ready to pounce again. What do you do?"