Recently the party, which at the time consisted of a druid, a rogue and a pair of warrior henchmen, was tracking down a band of undead looking for a dracolich's phylactery in the woods the druid was sworn to protect. They tracked them to the ruins of an ancient dragon cult where the party fought their way inside and descended into the bone pit below.
There they found a strange undead man standing near the back of the room (a revenant), a ghostly dragon (advanced ghost with a white dragon's breath attack), as well as several ghouls and ogre zombies. The players were nervously watching the revenant, not sure what to make of him and expecting that he'd turn out to be the true boss of the fight. As the battle started the PCs engaged the enemies, and the revenant did something that surprised them - he ran for the stairs. Even though the other party members were hard pressed, the druid decided to cast Entangle on the revenant, and he surprisingly failed his save. For the next six rounds, the revenant would improbably continue failing his saving throws against Entangle.
By this point the ghost dragon had been felled and only a few zombies remained. The revenant called out to his master and more zombies began climbing out of the bone pit, engaging the PCs and trying to keep them from the revenant. The rogue wasn't having it, and she danced past the zombies only to be stopped short by the revenant's vengeful glare. One of the henchmen fell to the zombies, and they moved up to try to break the druid's concentration. It was about this time that the revenant finally saved against Entangle. He began to move up the stairs but the rogue had saved against the paralysis and used an elemental gem to summon an earth elemental, which blocked the revenant's path. The revenant pummeled the elemental, though it inflicted good damage on him as well.
Only two or three zombies were still shambling, but the party was running on fumes as well. The rogue, unable to approach the revenant due to being frightened, chugged a few healing potions and used the last charge from her Bag of Tricks, unfortunately only summoning a rat. That rat would prove surprisingly useful in a few rounds when it crit the last remaining zombie, taking it down.
The remaining henchman was paralyzed by vengeful glare, the druid was fighting a losing battle with the revenant, and the rogue finally made her save to shrug off frightened. The revenant retreated to the upper temple and seemed to be about to get away when the rogue caught up to him. He swung at her, but missed twice. And with that, they managed to down him.
That encounter was set up with the possibility that they could stop the revenant, but I never actually expected them to pull it off. It was a deadly fight even without the revenant, and his goal was simply to get away with the phylactery intact. The players set their minds to it and pulled it off, despite that several times a TPK seemed imminent. And now the lich who sent the revenant has a reason to take a special interest in the PCs!
