Operation Bloodtalon
The party is level 7, and consists of a oath of the ancients paladin, a valor bard grappler, a sword-and-board battlemaster fighter, an infernal warlock, and a crotchety old abjurer who complains that his ex-wife was literally a succubus.
The party's paladin can communicate telepathically with his steed - a stag - so he sends the stag out as a far advance scout. He spots the army, and reports that there were maybe a hundred people, a few horses, some ox carts in the back, and a creature the size of an elephant. He sees a variety of wizards wearing differently-colored robes, and a short man with a very impressive hat who was riding atop the beast. They assume that this is the leader of the conspiracy, whom they dub the Pontiff.
The party figures they need more help, so they go kill a demonic hydra that has been causing trouble for some local fey. This nets them some allies; they have on their side 8 centaurs and 3 pixies. They also have an NPC sorceress and an NPC monk.
One player loves making maps, so I tell him the road parallels a river that heads to the town, and that the river averages about 100 feet wide. Then I tell him to go nuts drawing the map, because the party has time to pick where they'll spring their ambush. He draws a spot with woods on the northern bank, no cover no the southern bank, then the road, and south of it a couple of jutting hills with tree cover and undergrowth.
The party's paladin sends his stag to hang with the warlock on the north shore. The warlock is in charge of the centaurs. When he sees the army in the proper position, he'll tell the stag, who'll communicate with the paladin. This starts a count-down to give the rest of the party (hiding on the far side of the hill, south of the road) time to cast a suite of buff spells on the bard.
Before this, the pixies flit invisibly through the woods, assuming there'll be advance scouts. And there are. With the aid of invisibility, sleep, and arrows they manage to take out the three scouts before they can sound any alarm. Then the party scrambles back to their hiding spot.
Tromp tromp tromp tromp. The army marches closer. They can faintly hear a chorus of chants from the wizards (which the party never figured out were special battle wards to disperse incoming area effect spells like fireball). Riders in the front march past the party's hill, then a squad of twenty archers with a wizard, and behind them is the huge, armored, blue-furred beast with a howdah on top. The Pontiff sits with two soldier guards and a woman looking around warily.
The warlock gives the signal. Spells are cast on the bard - flight from a pixie, greater invisibility from the abjurer, enhance ability by the bard herself, bless by the paladin.
The Pontiff is perfectly positioned. The centaurs break from tree cover, and the warlock says, "the wizard in red." They fire a volley of arrows from 150 feet out, and even though only 5 hit, it knocks out the army's evoker. "Now the green one," the warlock says, and the centaurs' second volley fells the conjurer. The warlock himself then casts hypnotic pattern, which catches a huge mass of soldiers directly in front of the huge beast. They're entranced, and take no action at first. The centaurs finish their movement by riding back out of range of most spells.
After that moment of surprise, we roll initiative.
The army, initially confused by the ambush, moves slightly off the road toward the river, to take cover behind a few trees and brush. The surviving wizards ready to fireball the centaurs if they come back into range, and the commander of each squad orders his troops to ready to feather his target. None of the soldiers draw bows, but instead finger spell components.
The Pontiff shouts defiantly and readies a spell. The wand-wielder sitting next to him flies off the back of the beast, produces a bow out of nowhere, and manages to stick a few arrows in the centaur that the warlock is riding. (The warlock realizes this woman is actually a disguised erinyes.)
On the far side of the hill, the NPC sorceress uses her stone of controlling earth elementals to conjure an elemental beside the two riders in front, with orders to kill the horses (since the party plans to flee in a few moments). The elemental pops up and kills one horse. Its rider tries to fight back but doesn't accomplish much. A bard working with the army shouts for people to shake the hypnotized soldiers out of their confusion.
Our flying, invisible, strong, and blessed bard crests the hill and gets up to the side of the beast the Pontiff is riding in, but doesn't attack yet.
Across the river, the centaurs cut sideways and launch another volley, this time targeting the enchanter, but the Pontiff releases his spell - a blade barrier that slices the arrows to pieces. The centaurs launch a second volley at the illusionist (who isn't behind the blade barrier), but due to range, cover, and soldiers protecting him they only hit with a couple arrows, not enough to kill him.
The leader of one squad of soldiers magically casts a red light upon the earth elemental, and twenty soldiers as one cast a volley of magic missiles. This destroys the summoned monster. The soldiers all begin switching to bows, which suggests they only have one spell per day.
One of the surviving mages shouts that the elemental must have been summoned on this side of the river, and orders soldiers to check behind the hill. The erinyes still fires a few arrows at the warlock's centaur steed, and despite crazy range and cover manages to take out the centaur.
That's when the PC bard strikes. She grabs the Pontiff and flies back to the crest of the hill; the man's screams as he's yanked through the air catch the whole army's attention. With their target within sight, the party unloads. The fighter hurls javelins, the paladin uses a power of his magic sword to slash from afar, the NPC monk pops the man in the face with a flurry of rocks, and the NPC sorcerer blasts him. Then a pixie casts sleep on him. He goes out like a light. The abjurer creates a sleet storm in the one clear path between the hills, to slow the approach of the army.
The army starts to come anyway. The army illusionist tries to dispel the bard's invisibility (and we pause the game to see if he can target an area or if he has to go after a person he sees), but it doesn't matter, because his check fails. The huge beast gets prompted to charge around the hill on the other side, but it's slow going. The erinyes swoops in on the bard (whom she can see) and lays into her with sword swipes, horribly wounding her.
The bard fires off a fear spell that panics a squad of soldiers, then swoops down to the far side of the hill and takes cover by the fighter. The fighter coups the Pontiff. The paladin, sorceress, and monk launch some attacks at the erinyes, but don't drive her back.
The army's bard gets the enchanter to dimension door the both of them to the far side of the hill, where he casts mass suggestion to "stop fighting and dance with jazz hands." The abjurer counterspells it. The party swarms the enchanter and kill him, then horribly wound the army's bard. But the army is almost through the sleet storm, and they don't want to deal with scores more magic missiles. So the abjurer grabs the monk and dimension doors away. The bard grabs the fighter and dimension doors away. The sorceress NPC grabs the paladin and dimension doors away.
The party now has a 500-ft. lead, and they arrive near their horses, and they flee. The army is in disarray, demoralized, with only two casters left. The Pontiff who bound the erinyes is dead, so she skidaddles. They don't have sufficient spellcasting power now to perform the ritual they wanted in the first place, so they retreat.
Victory for the party.
