The briar timer forces your cycle to be length 6, and due to the arrows on the pressure plates, the only way that's possible is horizontal moves onto both. This tells you:
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×there must be a decoy in the same row as both plates, one further south than both and one further north.
Also, the move after a horizontal move can't be vertical (that would go back to the centre too soon), nor can it be diagonal in the same direction (since if another decoy was close enough for the diagonal push, it would prevent the horizontal push as well). So:
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×there are only three possibilities for the cycle, namely SW-E-NW-NE-W, SW-E-NW-NW-E and SE-W-NE-NW-W.
Now try to see why two of those can't possibly work, and you'll be left with the correct solution!
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50th Skywatcher
