K'Varn

K'varn is one of the major antagonists in Season 1 of the web series Critical Role. Originally, Vox Machina went searching for Lady Kima in Kraghammer after she disappeared to go stop a great evil from reaching the surface. After learning she ran into the Greyspine mines, the party followed and quickly discovered that this great evil and K'varn were the same. K'varn is first mentioned to the party by a Duergar that they had taken prisoner, and is revealed to be the one responsible for the modifications to the monsters in the Greyspine mines. As the party advances through the Underdark, they discover that K'varn is a massive Beholder, that it has acquired one of the Horn's of Orcus, and that it has captured the Elderbrain of Clarota's home colony, thus enslaving the entire city. Vox Machina prepares to fight K'varn over the course of episodes 8-11.

Temple Showdown
In order to defeat the beholder, the party drops a Fomorian giant to open the roof of K'varn's stronghold, and eventually kills it with a combination of repetitive damage, quick healing, and lucky saving throws. Even so, Grog is rendered unconscious, and escaped death only with Pike's quick help. Tiberius is noticeably absent from this fight, as he is terrified of the beholder's power.

Death
After K'varn falls to Vex's Hail of Thorns, the party rejoices, until they notice that the dark horn on K'varn's forehead is reviving him. This prods Tiberius into action, and after a failed attempt and some additional damage, he succeeds in ripping the horn from K'varn's forehead. This ends K'varn's life, and all of its magic, though the horn still holds power.

Artifacts

 * Horn of Orcus