To foe of His – I'm deadly foe – None stir the second time – (17-18)
This line is similar to the phrase "A friend of yours is a friend of mine," except replace "friend" with "foe." The speaker is saying that any enemy of her "Master" will get killed after the first time he "stirs." To "stir" can mean "to be aggressive," or in the most literal sense, "to move at all." If we saw it as a continuation of the doe image, then a stirring doe would certainly get shot just for moving if it were being hunted.