I ended up the session by saying (approximately),
As you enter the clearing, you hear the noise of pounding feet. A huge red lizard, fifty feet from nose to tail, lunges forward to grab a fleeing ogre. It flips him into the air like a rag doll, catches him in its mouth, and decapitates him with teeth the size of daggers. The ogre's head bounces on the ground and lands facing you. The head calls out, "Rescue my body, and I will owe you a mighty boon!"
I'm particularly pleased with the twist ending to that cliffhanger.
But since that evening, I've had a new appreciation for this technique of setting up the next combat at the end of the session, because of the salutary effects of having the players talk and think about what's coming up for a couple of weeks:
- It let's the players act better, because they've had time to think and plan. This in turn means that I can throw harder challenges at them.
- I think it builds anticipation: my players have been thinking about the fiendish tyrannosaurus and the horrors of its 5d8+13 bite, and thinking about the ways in which this fight could go badly wrong. This means that even if the fight becomes a pushover, there's still some thrill there.
- It lets me patch holes: if they talk about their plans beforehand and come up with an easy way to eliminate the excitement, it lets me think of ways to weasel around that if I want to.
- In the same vein, listening to my players' discussion gives me a chance to rule about potential rules issues ahead of time. For example, in the discussion last night, I pondered the issue of using dimension door to zip into the dinosaur's stomach, grab the ogre mage's body, and poof out (I ruled that it would work, but the problem might be the DC 23-30 Concentration check to get off the spell to bamf out), and about trying to get the halfling to ride the tyrannosaurus' neck and attack it without being attacked (possible, but a nasty Ride check).
so there's a lot of good here. I'll have to try this approach again.