This thread is tagged with "feedback" but there isn't any actual feedback yet. So I've figured I'd break the ice. I have no special talents or experience here - this is just one guy's opinion.
Good sense of action with this one in general.
This exercise is supposed to make every word matter so I'll nit pick. The word "explode" should itself come to the reader suddenly - i think it should come as early in the sentence as possible. You have "To her left a stone exploded, blinding her in glittering dust. " which buries the explosion in the middle of the sentence.
The phrase "Misaki charged." seems like it should be a big finale but it is robbed of some of its power by having "she charged" earlier on. Also "she" at the beginning and "Misaki" at the end made me question, for or moment, how many women were in the combat.
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This one manages to set a mood, tell a story, and have a twist. Excellent.
My only nitpick is the line "She darted around a corner he knew was a dead end, and he swaggered around it just in time to see her drop her mask." The first part is a little awkward, maybe because "she darted" is in the now, but "knew was" is in the past. This should also probably be two sentences.
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This one also manages to set the mood, tell a story, and add a twist all in a few word.
It feels to me like a first draft but I don't know why. Maybe its things like the tenses in "Jeffrey spat blood, straining against his chains", "Spat" is past tense but "straining" is present tense. "He drew a pistol, pressing it against Jeffrey's forehead. also seems to mix tenses.
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Anyway, those are my amateur attempts at feedback. Feel free to tear my "Siege" drabble apart in response.