Any thoughts or suggestions?
What's nice about 4e (which I know you likely all ready know) is that the PCs
could fight level 5 monsters at level 1. A standard encounter for a 6 man party is 600 xp; that's 3 ghouls right there.
Even so, I would actually suggest starting them around level 2-3. That way, there's a slight cushion, and it gets you closer to the real fun level (5), but not so far away, xp wise.
1) Prolong the adventure. Instead of it being a two-pronged siege or battle royale, the Ghouls and Gnolls are playing a shadow war at first. The ghouls introduce a highly infectious form of "Ghoul Fever", much like your typical zombie plague. All the while they stalk the streets, disguised as lepers and beggars, causing little bursts of havoc by starting a fire here, a riot there, destroying food and supplies to drive the citizens over the deep end into cannibalism.
The gnolls quarantine the town to prevent the disease (and the ghouls influence) from spreading further. They also send demon-possessed humans into the town under the guise of "holy men" and snake oil salesmen. The demon-possessed trying to convert the citizenry with Yeenoghu-venerating black rituals that stave off the fever, but of course it's corrupting the users and coaxing them towards the Butcher's way.
And smack dab in the middle is a town surrounded by hungry predators, trapped with a ghoul-raising disease, and in their midst are demon-infested zealots and ghoul anarchists whipping the town into a frenzy.
It might seem uncharacteristic for ghouls and gnolls to be operating with such patience and intelligence, but it's more like playing tug of war with a severed arm; it's a game that spirals into a gory mess. Scavengers
are sneaky and clever, after all.
So before the PCs ever see the first gnoll or full fledged ghoul, you can have them fighting possessed human warlocks, mobs of paniced people, house fires, humans near the end of Ghoul Fever (either undead, or rabies on steroids), murderous locals gone loco, anything the demon-possessed happen to summon into the town, and ghoul firebomber hide-and-seek.
2) The sodden ghoul (open Grave) is a level 4. Less powerful versions of the Ghoul. Like, in the first stages (first awakened); feral, strong but stupid brutes. Or something almost zombie like. Maybe a ghoul that has not fed (or has not fed in a long while) is a weaker version (Hey! Gnolls stealing food from ghouls = weakening them! Ha!)
3) Hyena are 2nd level monsters. Gnolls might also use demons (although there aren't many low level ones either). They could use slaves as hosts for demon possession.
4) Alter gnoll society a hint. I recall one poster saying that in his world, Gnolls are actually members of the Goblinoid family; Gnolls are the Religious leaders. (This also explained where Barghests came from; a crazy spiritual hybrid of goblin and hyena). If you went this route, you could be using all kinds of goblinoids backed up/lead by gnolls.
5) Before the G&G get there, you have other things happening. Maybe the gnolls are on the move, and are pretty much chewing through everything in the forest. This is driving local predators/weaker humanoids into the town because they're seeking "higher ground", so to speak. The mere
presence of the ghouls might be causing disturbances before they get there; increased ghost/undead/negative energy activity, etc. Play up "Something's coming and we don't know what", with ill omens, people going insane/rabid, and things of that nature that are symbolic of what's about to happen.
6) Finally, consider stuff from
this thread. The basis is objectives in combat that aren't related to killing the enemy to succeed. Maybe the PCs at first need to not fight, but instead get x number of townsfolk to safety, bar the gates, destroy five ritual sites, and so on. Don't focus on fighting the big bad monsters out there, make them work at surviving first.
