Help me defend a pass. (My players go away!)

[Inconsequenti-AL]

Given the large space to cover, I think Orc cavalry might be in order?

Normal cavalry could be very effective. Take some elite orcs - a bunch of Level 2 orc fighters on Light Warhorse Equivalents. Mounted feat chain + Lances = Ouchy! Could really ruin someones day.

With the right sort of cover, they could use ride by attack to make hit and run attacks while protecting themselves from counterattacks. Obscuring mist or a non magical equivalent might work?

Morrus really gave us hell with Orc archers riding undead poison breathing wyverns. Not nice and I never want to see them again.

 

[Conaill]

No. They have no idea who the PC's are, or when they might return, or even where they are. They are simply here to stop anyone form sneaking up behind the amassing army on the plains.

Ah! In that case, (1) they will likely be preparing for a larger military force, not a small party of heroes, and (2) their planned fortifictions won't be anywhere near finished yet!

That being said, I would assume the orcs have set up a walled wooden fort (the romans supposedly were able to set up camp in 6 hours... ditch, wall and all!). They probably also had enough time to dig a ditch and rampart across the entire 1/4 mile of the pass. And they would have started installing a pallisade on top of that rampart (still going with the roman camp model here). They would also have cleared the area in front of the ditch to create a nice killing ground, and have posted several scouts up ahead to give them advance notice. Depending on geography, they may also have built a tall watchtower, or set up scouts on top of a tall hill or mountain up ahead.

 

[BiggusGeekus]

If they don't know who or what are coming, then I agree they would be expecting a large army. That doesn't rule out your fort, as Conaill pointed out. But you are going to want a structure halfway built for flavor. If you can add a few orcs, I'd have a throwaway encounter with them being caught off guard prospecting for granite or building, well, anything really. The PCs would wipe the floor with them, but not all encounters should scale to level. Some should be too high so the PCs get scared and some should be too low to add to your world's versimilitude. This is a case where you're going to want an encounter that's "too low".

Hey, do you have Unearthed Arcana? There's a great bit in there about incantations. They're spells non-spellcasters can learn at the cost of exp. You have to spend a lot of time casting them and there's some other disadvantatages, but it might be cool to have one of your orcs be a 1st level adept who happend to know an incantation to summon a specific demon. That way you could introduce incantations to your players and have a reasonable justification for how the orcs were able to accomplish any specific thing you didn't think of that your players might call you on. Make the demon a small one, nothing too fancy. Later on, now that you introduced such a thing to your players, you can have them "interrupt a ritual" when another one of your NPCs summons up a big demon. That's always fun.

 

[Conaill]

[...]but it might be cool to have one of your orcs be a 1st level adept [...]

Actually, in a group opf this size, and given the standard D&D demographics, IIRC there should be at *least* one adept present. Pretty useful buggers too!