The game has a good ruleset to deal with issues just like this one.
Hobgoblin Warchief and Allies - may or may not know the party is there
Zombies - brains....
Kalarel and Co - sacrificing away
I would tee this up as a skill challenge of sorts. If the PC's can navigate it successfully, using stealth, perception, and insight, they can get two or three reasonable fights. If not, they are going to get gang-tackled. Just try to not have the combined encounter be greater than the "daily" tough encounter listed in the DMG, which I believe is Level +7. This is probably an EL 9 or 10 for your party at this point. That's a lot of xp's to play with.
I agree, if they should fail, then there is the chance that they will be in a very tough, very big encounter, with very poor tactical considerations (no exits, flanked, outnumbered, outclassed).
Good gaming!
Hobgoblin Warchief and Allies - may or may not know the party is there
Zombies - brains....
Kalarel and Co - sacrificing away
I would tee this up as a skill challenge of sorts. If the PC's can navigate it successfully, using stealth, perception, and insight, they can get two or three reasonable fights. If not, they are going to get gang-tackled. Just try to not have the combined encounter be greater than the "daily" tough encounter listed in the DMG, which I believe is Level +7. This is probably an EL 9 or 10 for your party at this point. That's a lot of xp's to play with.
I agree, if they should fail, then there is the chance that they will be in a very tough, very big encounter, with very poor tactical considerations (no exits, flanked, outnumbered, outclassed).
Good gaming!