The white horned horse was indeed a unicorn, named Weisslep. It spent time telepathically speaking with each party member to get a feel for them, and finally made itself fully known to them. Weisslep told them about a close by ruin which contained an artifact known as a Bileflow, which is a fountain-shrine dedicated to Chaos. These Bileflows were built thousands of years prior, and this one is the only whose location is known. The unicorn asked them if they would help destroy it, and all of the characters agreed to help.
The unicorn sent them down to the first level of the ruin, and told them to clear it out and return all found coin to him.
It was around this time too that the party realized while taking a long rest that Slow Natural Healing was now in effect. As the forces of Chaos are growing stronger, things are getting harder for the good folk...
After they cleared the first level and found passage to the next level blocked with magical mist, they returned up to Weisslep, who was joyful to see that they returned with honesty all of the coins they found. He then unblocked the passage to the second level, and sent them back down with a small vial of his own tears to pour into the Bileflow to destroy it.
On the second level they had a battle with a shield guardian who used a stored Banishment spell to send Riardon (the only caster who failed his save) to the Abyss to be tortured by devils. The rest of the party finally took down the construct, bringing the druid back.
At this point, I had the players roll 3d6 to determine their sanity scores. This optional rule is now officially part of the Cairnvarthi campaign. Riardon then had to make a sanity save, which he failed.
They poured Weisslep's tears into the Bileflow, turning it from a terrifying, nausea-inducing fountain of flowing evil sludge into a verdant, gorgeous fountain pulsing with the energy of Silvanus and Skadi.
When they surfaced, Weisslep was beyond pleased, and then became a conduit for divine blessing as the entire party was shifted to Good alignments. "Want hard as you might to be uncaring or wicked, you are all good folks, and you have just proven that beyond doubt. May the gods be with you on your journey."
The group then found themselves teleported to the edge of the forest, where they could see a road a few miles off to the east. "North should do you fine," said Weisslep, "South shouldn't kill you either." With those final words, the unicorn disappeared.
Of course, they chose to go west, back into the forest, to explore.
The first day of travel back into the forest netted them an encounter with some orcs who were led by a Chaos shaman. It was a most unsuccessful ambush for the goblinoids. At this point the group had hit some steep mountains which were impassable, and they decided to head south to go around them so as to continue their westward decision.
The next day around noon, the heroes were attacked by a handful of giant spiders who were led by a couple of ettercaps. Once again, the party made quick work of them.
Around 5pm that evening, as they came close to the southern portion of the mountains, the druid and the ranger started noticing that the underbrush was growing thick and terribly thorny, and all of the party started noticing a slight hint of chlorine in the air. About an hour later, a large draconian shadow glided over them. Shortly thereafter, they came upon a path. Marked with humanoid skull covered pikes, to the left it wound into the forest, and to the right it followed a rough hewn path up the mountain for about fifty yards before ending at some ruins. They could see the large green beast circling above them in the air.
Once there, they discovered the smallest remnants of the four walls of a 100' square keep. Towards the center, enough flagstones remained of the floor to keep the top of a spiral staircase which descended into the ground from being over grown so much that it couldn't be seen. The group descended about 15' down to revive the druid and lick their wounds safely away from the wyrm. While they were doing so, horrible, gurgling-wet screams and footsteps echoed from below them,and in a short time they were beset upon by zombie goblins. After making work of them, they descended to find more zombie goblinoids.
At this point, they have explored a few rooms in, and encountered goblins, orcs, and even a couple of ogre guards. They also found a map that hopefully shows them where they are.
We'll pick up from there next week!