In Sunday's game, the PCs encountered a very tough monster. I didn't name it, but I did describe using some exact wording. And I've been dropping blatant hints that there was one in my dungeon. After all, I knew it would be there - I'd planned on this one being in the place since I'd first started mapping it.
It was a Black Reaver, straight out of Rolemaster Companion, one of my favorite RPG supplements.
I don't think any of the players at the table recognized it.
But at least one who missed the session did - he'd encountered one before in a game I'd run.
At least in Rolemaster, and possibly in my DF game, there are two kinds of black reaver - the black reaver, and the lesser black reaver. The first one's description includes the line "There is nothing short of a deity more dangerous than a Black Reaver."
The lesser ones?
The "Lesser Black Reavers are not so over-whelming in their power, though certainly more dangerous than an average large Dragon!"
I'll let the PCs draw their own conclusions about this one. But it's certainly tough. I mentioned them before as trick monsters and when I talked about using your favorite monsters right away. And they came up on the rumor table.
The PCs will be researching them, and I'll share here all that they learn. If you want to know the inspirational material, check out the Rolemaster Companion or Creatures & Monsters.