I ran a Harn Campaign where-in the PCs were under orders to ransack a wizard's tower. In his absence, the wizard had summoned a satyr and a tiger to guard his crib. The satyr didn't like the wizard much, but was bound to attack anyone that came too close. When the PCs approached, he hailed them and explained the situation;

"Terribly sorry, chaps, but the situation is this. And it's likely that my tigery friend will rend you all limb from limb, so why don't you save us all a lot of aggravation and go home, hm?"

The satyr hinted that there was another entrance not covered by is binding, and the PCs found it eventually.* When they tried to exit from the front door, the satyr popped into view just to remind them that it would best to leave the way they came.

I thought this was a lot more fun than the usual "- aaand everyone roll init!" style of play. To their credit, the players didn't just run in and cut the bugger down, either.

I had intended to use the satyr again later, but the campaign fizzled out. I can't even remember his name, now! *sigh*

Ned