I'm re-writing the "Battle of Albridge" encounters from The DM-kit's Reavers of Harkenwold. As supplied they are mostly just a rehash of earlier fight-to-the-death skirmishes on re-used maps. Instead my party wants to plan an ambush at the bridge. Dramatically, I think that should be the second encounter in this milestone, and the first should be a delaying action fought south of town (to give the villagers more time to prepare (wait for the morning fog to lift, etc.)
I've added more forces to the bad-guys, and prepared a nice choke point along the Kings Road that you can see here:
Here's an excerpt from my read-aloud text:
"Keep as few Iron Circle forces from reaching the bridge before we're ready [RR rounds], that's the longest we can afford to have you away from the bridge. Return after MM minutes, no matter what! Do the best you can, but be sure to return, even if they overrun you quickly."
The number of enemy troops that get off the north (top) end of the map in the allotted time will determine the success of the encounter (XP and starting forces in the next encounter). In effect, this is a combat (instead of skill) challenge.
I've never run a 4e delaying-action combat before so I need advice - What should RR and MM be above?
Let's say that the characters are facing a force that is 2x the normal XP budget for their level. Is there an example of something published somewhere I can look at? I have access to a lot of 3e books and a DDI subscription...
If you've run something like this before, did you learn anything that might help me run this?