13 actually works out, because there are 12 normal moons in the year, and then we can add a special moon like "Blood Moon" (which actually fits the theme quite well!). Now that I think about it, harvest doesn't quite work, because October's moon is the "Harvest moon" so year 10 fall would be "Harvest of the Harvest Moon" which doesn't quite roll off the tongue...
Let's go with:
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$turnLabels = array("Wolf", "Snow", "Worm", "Pink", "Flower", "Strawberry", "Buck", "Sturgeon", "Corn", "Harvest", "Frost", "Cold", "Blood");
return ("Year ").(floor($turn / 26) + 666).(", ").($turn % 2 ? "Ruin" : "Advent").(" of the ").($turnLabels[($turn / 2) % 13] ).(" Moon");
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