Rolling randomly, our terrain is grasslands. I rolled "Unusual" for the encounter type (uh-oh). The result was Gorgons! Fortunately for our hypothetical party, they only meet one; just one measly, little, armor-plated bull with a petrification attack.
Encounter distance come up at 40 yards. Given that this boulder-making bovine can cover that in a single round, that's pretty close. Let's assume the PCs came over a hill and there it was on the opposite side; maybe just down the slope?
Next up, since there isn't anything in particular in the gorgon's description to indicate a default reaction, and it's of animal intelligence, let's make a reaction roll. An 8 indicates uncertainty and no immediate attack. If the players don't rush it, they might be able to just back away and avoid the fight. Let's assume they try to calm the beast with soothing noises and move around it. A second reaction roll gives us an 11! Since there was no offer to consider, it's fair to say the beast wanders off. Crisis averted.
Or was it?
One of the issues with random encounters like that is if you meet the monster away from its lair, then you're a lot less likely to see any treasure. A gorgon has type E treasure, and since it's a beast, it's not carrying its loot around with it. Greedy players might decide to follow the gorgon and see if it leads them to its lair. Rolling for the Number Appearing in lair (1d4), I got a 2; which means another one (its mate?) is back at the old homestead.
Let's assume the fight occurs and the PCs win (at least some of them). That's not so crazy. Heck, if they can down one of them, maybe the other fails its lousy morale. So what was their fabulous reward? Well, TT: E is listed with an average value of 2,500gp (B45), but we're doing random here! So I rolled for it. Turns out, the PCs did pretty well for themselves.
- 1,000gp in gold coin/buillion
- 9 gems (!), totaling 2,400gpv (including one 1,000 gpv stone)
- 7 pcs of jewelry (!!), totaling 7,500gpv. The highest value piece rolled at 1,500gpv alone.
This give a grand total of 10,900gp worth of loot!
Defeating the gorgons is worth 2,400xp (8HD + special each). So the party could walk away from that with over 13K xp to split amongst them.
This is why PCs sometimes foolishly pursue risky encounters unnecessarily. Sometimes, just sometimes, it can pay off.
Now, that's the bones of the encounter. Let's put some meat on it.
I don't think we need to do much to explain the gorgons' presence. They are listed as living in grasslands, so that's just their habitat. How they heck did they get all that swag though?
Since as treasures go this has got a pretty high value-to-size ratio and is almost all in gems/jewels, it seems more likely to have come from one place than have been collected from many sources. Who has such things? Nobles do, but it seems odd for them to have been out on the prairie dripping in pearls. That doesn't explain the loose stones or the gold coin, either. So here's my idea:
Years ago (how long is up to the DM), a young gentlewoman was promised in marriage to some horrible old nobleman, but she was in love with a poor commoner-type. She decides to flee in the night, taking enough easily portable wealth for her and her paramour to start anew. Galloping madly cross country to meet him in the next town, she accidentally stumbled across the pair of gorgons. Her horse shied and threw her as it bolted, causing her to drop the bag of treasure. Thus, when the startled monsters breathed their petrifying fog, only she was turned to stone, not the gold, etc.
When her father's men searched for her, the fleeing horse's tracks led them off in the wrong direction. The stone figure of the girl and the small leather bag lying in the tall grass were all but invisible to searchers. The gorgons had wandered off but eventually returned to their preferred resting spot. Over the years, the gorgons and their kin have made the area around this hollow their home.
Perhaps the story of the lass and the treasure is a local legend. Maybe the lad was found out and it was assumed he killed her for the loot. Maybe he's been executed and he haunts the girl's family to this day. If the PCs find the petrified girl when they find the loot, a whole new adventure arc could spawn from a simple random encounter.
Assuming the PCs don't go full murder-hobo and just leave the girl as a rock and take the loot. Those Stone to Flesh scrolls ain't cheap!