So I'm always looking for good ideas for encounters. 4E's combat can take quite a bit of time and its important to make sure that the battles are interesting. So I'm interested in people describing some of their favourite encounters and what made them so great. That way we might be able to steal some good ideas off each other.
One of my favourites was from Bordin's Watch (I think - I was a player).
The premise of the encounter is that Orcs are attacking through the sewers(?) and the PCs need to get to this mechanism in this room to close off the sewers and then escape.
The room was large with a ramp that ran around edges slowly climbing higher as it circled the room. There was a kind of tower in the middle of the room that could be reached easily from the ramp but only near the top. There where entrances into the room leading onto the ramps every 40 feet or so. The room had some powerful Orc baddies but their real problem was a constant influx of Orc minions into the room. The result was a desperate race toward the tower so we could perform the skill challenge necessary to close the grates and stop the constant influx of Orcs.
This created a series of interesting choices for the group on who would cover the rear, how we where going to fight our way forward and eventually a gambit where we sent the rogue to climb up the tower to start on the skill challenge and we just hoped we could fight pour way to his relief in time.