My D&D Group needs a really good encounter

[LostSoul]

See if you could have them fight a wounded version of themselves. They warp in from the future and begin a fight. It should be pretty challenging.

Then listen to the players wonder why they would want to kill themselves in the past. Take the best couple of ideas, throw your own spin on it, and run with it.

 

[ForceUser]

Well, a dragon has a certain "classic" appeal, but groups are more effective, tactically. More spells, more chances to hit.

How about a group of dragons?

Also, don't discount a single wurm. While it's true that prepared parties can whomp on a draco, consider the reverse: a prepared dragon ambushing the party! Consider the filty possibilities...