Harpy
About
They come down onto the table rather than onto the people, and that is the point of them. Harpies snatch, foul and ruin - the meal, the stores, the water butt, the bandages - and they are gone up into the rocks before anyone has drawn. A party that fights one off and congratulates itself will discover the actual cost three days later, four days from anywhere, with nothing left to eat.
Stats
Save Rolls
Traits
Special Attack
Snatch and Foul: slashing, melee 5 ft, +3 to hit, 2d6+2 (two strikes with claws), and on any hit it takes or spoils one item of food, water or supply rather than pressing the attack. Stench: 10 ft, save Con Tough, fail save roll 2d6+2 poison and the target is Weary until it rests, cooldown 3 rounds.
Special Defense
Takes and Goes: it disengages upward after any successful snatch and will not stay to fight a party that has nothing left worth taking. Ruin, Not Slaughter: everything it spoils is spoiled permanently - no roll, no save. Rations, waterskins, poultices and spell components are simply gone, and the DN should make the party account for them.