Ettin
Explorer
I know you were making a suggestion. It just has nothing to do with Celtic adventuring, especially since your follow-up post about people as rewards there reads like a standard D&D adventure too. (And if he's running so low-fantasy even his orcs are humans, like he said in the OP, suggesting trolls instead probably isn't going to work.)
How do you handle "beautiful women" as a treasure? Do the PCs receive less in the way of other possessions like gold and magical items?
Are there charts?
The Celts had a lot of legends about fey and such. Using actual fey would probably ruin your low-fantasy setting, but it could help if you need to add background flavour (normally townsfolk don't go into the forest at night because they think there are fey there, or they leave offerings if they pass through certain places, etc.).
The Romans were around about the same time as the Celts, too, so imperialistic foreign soldiers antagonising their hometown might work for either a short adventure or a campaign depending on how many soldiers you want to throw in.
And yeah, I also second looking at barbarian adventure stories for ideas.
